JP6487869B2 - Work vehicle - Google Patents

Description

  The present invention relates to a work vehicle such as a farm work machine such as a tractor or a combiner or a special work machine such as a crane truck or a back fore.

  2. Description of the Related Art Conventionally, a work vehicle such as a farm vehicle such as a tractor or a combiner or a construction machine such as a crawler crane has been provided with two hydraulic continuously variable transmissions (HST) to which power from an engine is transmitted. Some types of continuously variable transmissions output straight power and turning power based on engine output (see, for example, Patent Document 1). The present applicant has proposed a work vehicle in Patent Document 2 that can turn by combining the straight power and the turning power output from the two hydraulic continuously variable transmissions by the left and right planetary gear mechanisms. .

  In addition, some conventional work vehicles include a transmission case that transmits power from an engine and a hydraulic mechanical transmission (HMT) that has higher transmission efficiency than a hydraulic continuously variable transmission. The applicant of the present application has previously made a series-type (in-line type) hydraulic mechanical transmission in which the hydraulic pump and the hydraulic motor are arranged in series so that the input shaft of the hydraulic pump and the output shaft of the hydraulic motor are positioned concentrically. Is proposed in Patent Document 3.

  In an inline type hydraulic mechanical transmission, an output shaft is fitted on an input shaft to which power is transmitted from an engine so as to be relatively rotatable. Further, a hydraulic pump, a cylinder block, and a hydraulic motor are fitted on the input shaft. The cylinder block alone serves as both a hydraulic pump and a hydraulic motor, and power is transmitted from the hydraulic motor to the output shaft. For this reason, unlike a general hydraulic mechanical transmission, an in-line type hydraulic mechanical transmission can output a combination of hydraulic shift power and engine power without interposing a planetary gear mechanism. It has the advantage that transmission efficiency can be obtained.

  Further, the applicant of the present invention provides a forward / reverse clutch, a main transmission mechanism, and a sub-transmission mechanism in a mission case in a work vehicle including a transmission case that receives an output from the engine and changes gears. It has been proposed that the output is combined with the output from the auxiliary transmission mechanism as turning power by a hydraulic mechanical transmission.

Japanese Patent Laid-Open No. 2002-200925 JP-A-10-271905 Japanese Patent Laying-Open No. 2005-083497 Japanese Patent Laying-Open No. 2005-212612

  Incidentally, in order to mount the hydraulic mechanical transmission in Patent Document 3 on a medium-sized or large work vehicle, it is necessary to increase the output of the hydraulic mechanical transmission. In order to increase the output of the hydraulic mechanical transmission, for example, the capacity of the hydraulic mechanical transmission can be increased. However, simply increasing the capacity of the hydraulic mechanical transmission not only increases the size of the hydraulic mechanical transmission itself but increases the manufacturing cost, but also sacrifices the power transmission efficiency (especially in the low load range). There was a problem.

  Further, since the traveling vehicle of Patent Document 4 has a configuration in which the hydraulic mechanical transmission is disposed only in the turning transmission path, the linear transmission transmission path is stepwise depending on the gear ratio of the main transmission mechanism or the sub-transmission mechanism. In some cases, the power desired by the operator cannot be obtained. Furthermore, since the power input to the turning system transmission path is input from the engine via the main transmission mechanism, the power in the transmission case is determined by the swash plate position and the hydraulic fluid viscosity in the hydraulic mechanical transmission. This may affect not only the driving of the main transmission mechanism and the sub-transmission mechanism but also the engine start.

  This invention makes it a technical subject to provide the working vehicle which examined and improved the above present condition.

A work vehicle according to the present invention includes an engine mounted on a traveling machine body, a traveling unit that is driven based on the power of the engine , and a first continuously variable transmission that shifts output from the engine and outputs power for straight travel. A second continuously variable transmission that shifts the output from the engine to output turning power, and a power combining mechanism that combines the straight driving power and the turning power, from the power combining mechanism In a work vehicle in which the left and right traveling units are independently driven by the power of the engine, a turning clutch mechanism is provided between the engine and the second continuously variable transmission, and the driving of the traveling unit is abnormal. When this occurs, the turning clutch mechanism is disconnected.

  In the work vehicle, when an abnormality occurs in the driving of the traveling unit, the straight power by the first continuously variable transmission is stopped, and then the turning clutch mechanism is disconnected to stop the turning power. It is good also as what makes it.

In the work vehicle, which amount pivot by the driving unit, determines when it becomes the turning amount and mismatch, which is set with respect to the steering angle of the steering longitudinal handle, that an abnormality in the driving of the traveling portion is generated It is good.

In the work vehicle, straight brake mechanism is provided between the power combining mechanism straight advancing clutch mechanism, when an abnormality occurs in the driving of the traveling unit, the power combining by said linear brake mechanism The turning clutch mechanism may be disconnected after the straight driving power input to the mechanism is braked.

  According to the present invention, when an abnormality occurs in the driving of the traveling unit, the turning clutch mechanism is disconnected, so that a turning operation unintended by the operator can be prevented, and the work vehicle can be safely emergency-stopped when the abnormality occurs. it can.

  According to the present invention, when an abnormality occurs in the driving of the traveling unit, to stop the turning power after stopping the straight traveling power, the traveling speed of the traveling unit is reduced and the turning amount is reduced at the same time. Not only can emergency stop be performed smoothly, but operator safety can be ensured. Further, by completely stopping the turning power, it is possible to prevent the unexpected turning of the operator, and the safety can be further improved.

It is a left view of a tractor. It is a right view of a tractor. It is a top view of a tractor. It is a left view of a traveling body. It is a right view of a traveling body. It is a top view of a traveling body. It is a plane explanatory view of a control seat part. It is a perspective view which shows the structure of the steering handle periphery. It is a perspective view which shows the connection structure of a brake mechanism and a brake pedal. It is explanatory drawing which shows the relationship between the hydraulic oil discharge amount of a hydraulic mechanical transmission, and a vehicle speed. It is a skeleton figure of the power transmission system of a tractor. It is a hydraulic circuit diagram of a tractor. It is a front expansion perspective view of a traveling machine body. It is a perspective view which shows the structure inside the turning mission case. It is a perspective view which shows the structure of the clutch mechanism for rotation. It is a partial cross section figure of the mission case for turning. It is a skeleton figure of the power transmission system in the turning mission case. It is an expanded sectional view which shows the structure of the clutch mechanism for rotation. It is explanatory drawing which shows the relationship between the clutch mechanism for turning, and a clutch position switching mechanism. It is explanatory drawing which shows operation | movement of a clutch position switching mechanism. It is a block diagram which shows the structure of the control system of a tractor. It is block explanatory drawing which shows the structure of the traveling control system of a tractor. It is explanatory drawing which shows the relationship of the parameter memorize | stored in the deceleration rate table and the turning / straight-running ratio table. It is a flowchart which shows the traveling control of a tractor. It is a flowchart which shows emergency stop control of a tractor. It is a flowchart which shows another example of emergency stop control.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings for a farm tractor. As shown in FIGS. 1 to 6, the traveling machine body 2 of the tractor 1 is supported by a pair of left and right traveling crawlers 3 as traveling portions. A diesel engine 5 (hereinafter simply referred to as an engine) is mounted on the front of the traveling machine body 2, and the traveling crawler 3 is driven by the engine 5 so that the tractor 1 travels forward and backward. The engine 5 is covered with a bonnet 6. A cabin 7 is installed on the upper surface of the traveling machine body 2. Inside the cabin 7, a steering seat 8 and a steering handle 9 for steering the traveling crawler 3 are arranged. Steps 10 on which the operator gets on and off are provided on the left and right outer sides of the cabin 7. A fuel tank 11 for supplying fuel to the engine 5 is provided below the left and right sides of the cabin 7. The fuel tank 11 is covered with left and right rear fenders 21. A battery 817 that supplies power to the front of the fuel tank 11 is provided on the left side of the cabin 7, and is covered with the left rear fender 21 together with the fuel tank 11.

  The traveling machine body 2 includes an engine frame 14 having a front bumper 12 and a turning mission case (drive axle) 13, and left and right machine frame 15 detachably fixed to a rear portion of the engine frame 14. The axle 16 is rotatably projected outwardly from the left and right ends of the turning mission case 13, and axle cases 90 covering the axle 16 are provided on both the left and right sides of the turning mission case 13. Drive sprockets 62 are attached to the left and right ends of the turning mission case 13 via axles 16. The rear portion of the body frame 15 is connected to a straight transmission case 17 for appropriately shifting the rotational power from the engine 5 and transmitting it to the drive sprocket 62.

  As shown in FIGS. 1 to 4, left and right track frames 61 are arranged on the lower surface side of the traveling machine body 2. The track frame 61 extends in the front-rear direction and is provided in a pair of left and right sides, and is positioned on both outer sides of the engine frame 14 and the body frame 15. The left and right track frames 61 are connected to the engine frame 14 and the body frame 15 by a lower frame 67 extending in the left-right direction. The front ends of the left and right track frames 61 are connected to axle cases 90 provided on both left and right sides of the turning mission case 13. On the outside of each of the left and right track frames 61, a step 10a on which the operator gets on and off is provided.

  The left and right central portions of the lower frame 67 are fixed to the rear side surface of the engine frame 14 via a connection bracket 72. The left and right ends of a beam frame 68 extending in the left-right direction are connected to the middle part of the left and right track frames 61 in the front-rear direction. The center of the beam frame 68 is connected to the center of the lower frame 67 via a reinforcing frame 70 provided in the front-rear direction. Rear beams 73 projecting inward at the rear of the left and right track frames 61 are connected to rear housings 74 fixed to the left and right side surfaces of the straight traveling mission case 17 so that the rear part of the track frame 61 is connected to the left and right side surfaces of the transmission case 17. Fix it.

  The track frame 61 includes a drive sprocket 62 that transmits the power of the engine 5 to the traveling crawler 3, a tension roller 63 that maintains the tension of the traveling crawler 3, and a plurality of track rollers that hold the ground side of the traveling crawler 3 in a grounded state. 64 and an intermediate roller 65 that holds the non-grounding side of the traveling crawler 3. The driving sprocket 62 supports the front side of the traveling crawler 3, the tension roller 63 supports the rear side of the traveling crawler 3, the track roller 64 supports the grounding side of the traveling crawler 3, and the intermediate roller 65 supports the non-traveling crawler 3. Support the ground side. The tension roller 63 is rotatably supported by a rear end of a tension frame 69 configured to be extendable and retractable rearward from the rear end of the track frame 61. The track roller 64 is rotatably supported on the front and back of an equalizer frame 71 supported on the lower part of the track frame 61 so as to be swingable back and forth.

  Further, a front dozer 80 can be mounted on the front portion of the tractor 1. A pair of left and right dozer brackets 81 are fixed to the front side surface of the engine frame 14, the axle case 90, and the lower frame 67, and a U-shaped (U-shaped) support arm 83 of the front dozer 80 in the plan view is The dozer bracket 81 is pivotally supported so as to be detachable on the outside (machine outside). The left and right dozer brackets 81 have a front end inside (machine inside) connected to the side surfaces of the left and right engine frames 14, a rear end lower side connected to the upper surface of a middle part of the lower frame 67, and a midway part in the middle of the axle case 90. It is connected so that it can be held up and down. The dozer bracket 81 can be secured to the three bodies of the engine frame 14, the axle case 90, and the lower frame 67, thereby ensuring the strength to withstand heavy work by the front dozer 80.

  A hydraulic lifting mechanism 22 that lifts and lowers the ground working machine 18 such as a rotary tiller is detachably attached to the rear part of the straight traveling case 17. The ground work machine 18 is connected to the rear part of the straight traveling case 17 through a three-point link mechanism 111 including a pair of left and right lower links 23 and a top link 24. A PTO shaft 25 for transmitting a PTO driving force to the ground work machine 18 is provided on the rear side surface of the straight traveling mission case 17 so as to protrude rearward.

  As shown in FIGS. 4 to 6, a flywheel 26 is attached to the rear end of the output shaft (piston rod) 5 a of the engine 5 projecting rearward from the rear side surface of the engine 5. A main shaft 27 projecting rearward from the flywheel 26 and an input counter shaft 28 projecting forward from the front side of the straight traveling mission case 17 are connected via a power transmission shaft 29 having universal shaft joints at both ends. . The straight output shaft 30 that protrudes forward from the lower front portion of the straight transmission case 17 has a linear input counter that protrudes backward from the turning mission case 13 via a power transmission shaft 31 having universal joints at both ends. The shaft 508 is connected. The front end of the output shaft (piston rod) 5a of the engine 5 protruding forward from the front side surface of the engine 5 protrudes rearward from the turning mission case 13 via a power transmission shaft 711 having universal joints at both ends. The turning input counter shaft 712 is connected.

  As shown in FIGS. 1 to 6, the hydraulic lift mechanism 22 is provided with lift fulcrums on the left and right hydraulic lift cylinders 117 that are controlled by operation of the working unit position dial 51 and the upper lid of the transmission case 17. Left and right lift arms 120 that pivotally support the base end side through a shaft so as to be rotatable, and left and right lift rods 121 that connect the left and right lift arms 120 to the left and right lower links 23 are provided. A part of the right lift rod 121 is formed by a horizontal cylinder 122 for hydraulic control, and the length of the right lift rod 121 is configured to be adjustable by the horizontal cylinder 122. When the ground work machine 18 is supported by the top link 24 and the left and right lower links 23, the piston of the horizontal cylinder 122 is expanded and contracted to change the length of the right lift rod 121. The tilt angle is changed.

  Next, the internal structure of the cabin 7 will be described with reference to FIGS. A steering column 32 is disposed in front of the control seat 8 in the cabin 7. The steering column 32 is erected in a state of being embedded in the back side of the dashboard 33 disposed on the front side inside the cabin 7. A steering handle 9 having a substantially round shape in plan view is attached to the upper end side of the handle shaft that protrudes upward from the upper surface of the steering column 32. A steering angle (steering angle) detection mechanism 880 having a steering angle sensor 821 for detecting the steering angle of the steering handle 9 is connected to the lower end of the handle shaft in the steering column 32.

  On the right side of the steering column 32, a work machine lifting lever 34 for raising and lowering the hydraulic lifting mechanism 22 and a brake pedal 35 for braking the traveling machine body 2 are arranged. On the left side of the steering column 32, the forward / reverse switching lever 36 (reverser lever) for switching the traveling direction of the traveling machine body 2 between forward and reverse, and the hydraulic clutches 537, 539, and 541 for power transmission are shut off. A clutch pedal 37 for operation is provided. A parking brake lever 43 for holding the brake pedal 35 in the depressed position is disposed on the rear side of the steering column 32.

  An erroneous operation preventing body 38 (reverser guard) extending along the forward / reverse switching lever 36 is disposed on the left side of the steering column 32 and below the forward / reverse switching lever 36. By disposing an erroneous operation prevention body 38 as a contact preventer below the forward / reverse switching lever 36, the operator is prevented from inadvertently contacting the forward / reverse switching lever 36 when getting on and off the tractor 1. An operation display panel 39 incorporating a liquid crystal panel is provided on the upper rear side of the dashboard 33. An emergency stop switch 58 for urgently stopping the tractor 1 is disposed on the steering column 32.

  An accelerator pedal 41 for controlling the rotational speed of the engine 5 or the vehicle speed is arranged on the right side of the steering column 32 on the floor plate 40 in front of the control seat 8 in the cabin 7. Note that substantially the entire top surface of the floor plate 40 is formed as a flat surface. Side columns 42 are arranged on both the left and right sides of the control seat 8. Between the control seat 8 and the left side column 42, an ultra-low speed lever 44 (creep lever) for forcibly and greatly reducing the traveling speed (vehicle speed) of the tractor 1 and a traveling sub-shift in the straight traveling mission case 17 are provided. An auxiliary transmission lever 45 for switching the output range of the gear mechanism and a PTO transmission lever 46 for switching the drive speed of the PTO shaft 25 are arranged.

  Between the control seat 8 and the right side column 42, an armrest 49 for placing an arm or elbow of an operator seated on the control seat 8 is provided. The armrest 49 is configured separately from the control seat 8 and has a main transmission lever 50 that increases and decreases the traveling speed of the tractor 1 and a dial that manually changes and adjusts the height position of the ground working machine 18 such as a rotary tiller. A working unit position dial 51 (elevating dial) and a work implement elevating switch 57 for elevating the hydraulic elevating mechanism 22 are provided. In addition, the armrest 49 is configured to be able to be turned up and rotated in a plurality of stages with the rear end lower part as a fulcrum. In the present embodiment, the vehicle speed of the traveling machine body 2 increases when the main transmission lever 50 is tilted forward, while the vehicle speed of the traveling machine body 2 decreases when the main transmission lever 50 is tilted backward. Furthermore, the armrest 49 includes a potentiometer (variable resistor) type main transmission sensor 822 (see FIG. 13) that detects the forward / backward tilt of the main transmission lever 50.

  The right side column 42 has, in order from the front side, an operation monitor 55 having a touch panel function and capable of commanding each part of the tractor 1, a throttle lever 52 for setting and maintaining the rotational speed of the engine 5, and the PTO shaft 25. A plurality of hydraulic pressures for switching between a PTO clutch switch 53 for intermittently transmitting power to the ground work machine 18 such as a rotary tiller and a hydraulic external take-off valve 430 disposed on the upper surface side of the straight traveling mission case 17. An operation lever 54 (SCV lever) and a single / double acting switch 56 for switching the double acting valve mechanism 431 disposed on the front surface of the rear housing 74 are disposed. Here, the hydraulic external take-off valve 430 is for controlling supply of hydraulic oil to hydraulic equipment of another work machine such as a front loader retrofitted to the tractor 1. The double-acting valve mechanism 431 is for operating the hydraulic lift cylinder 117 in a double-acting manner by operating together with the elevating valve mechanism 652 disposed on the upper surface side of the straight traveling mission case 17.

  Next, the relationship between the brake pedal 35 and the brake mechanism (brake mechanism for straight travel) 751 will be described mainly with reference to FIGS. 8 and 9. In front of the steering column 32, a brake pedal support bracket 916 that supports the brake pedal shaft 755 is fixed to the back surface of the board support plate (air cut plate) 901 (the control seat 8 side). The base end boss portion 35a of the brake pedal 35 is fitted on the brake pedal shaft 755, and the base end boss portion 35a of the brake pedal 35 is connected so as to rotate integrally with the brake pedal shaft 755.

  A pedal shaft arm 756 protruding forward is fixed to both ends of the brake pedal shaft 755, and the pedal shaft arm 756 rotates together with the brake pedal shaft 755. Note that the base end boss portion of the clutch pedal 37 is also fitted to the brake pedal shaft 755 so as to be rotatable. A clutch position sensor 829 (see FIG. 13) and a brake position sensor 828 are fixed to the left and right ends of the brake pedal shaft 755, respectively. A brake switch 851 is disposed at a position facing the pedal arm 35b of the brake pedal 35, and a clutch switch 852 (see FIG. 13) is disposed at a position facing the pedal arm 37b of the clutch pedal 37.

  A pair of left and right brake operation shafts 757 are supported on the left and right lower sides of a board support plate (air cut plate) 901. A link boss body 758 connected to the brake arm 752 of the brake mechanism 751 in the turning mission case 13 is rotatably fitted to the left brake operation shaft 757. A link arm 759 projecting from the outer peripheral surface of the link boss body 758 has a two-stage expansion / contraction that makes the braking operation of the brake mechanism 751 stepwise and the lower end of a vertically long link rod 762 connected to the left pedal shaft arm 756. The upper end of the link body 763 is connected. The lower end of the two-stage telescopic link body 763 is connected to the tip of the link arm 767 at the rear end of the brake rod 766. The brake rod 766 is supported by link support brackets 764 and 765 fixed to the engine frame 14 and extends in the front-rear direction. The link arm 768 at the front end of the brake rod 766 is connected to the brake arm 752 of the brake mechanism 751 in the turning mission case 13 via the connecting plate 753.

  That is, the left end of the brake pedal shaft 755 is connected to the brake arm 752 of the brake mechanism 751 via the link rod 762, the two-stage telescopic link body 763, and the brake rod 766. Therefore, as the brake pedal shaft 755 rotates as the brake pedal 35 is depressed, the brake arm 752 can be rotated, and the braking operation by the brake mechanism 751 can be executed. At this time, when the two-stage telescopic link body 763 acts, the amount of stepping for sudden braking is larger (the brake mechanism 751) than when the amount of stepping for adjusting the traveling speed is small (the play area of the brake mechanism 751). The braking force applied to the brake pedal 35 is increased in the braking region).

  A link boss body 760 having a link arm 761 is rotatably fitted to the right brake operation shaft 757. The upper end of a two-stage telescopic link body 769 for stepping on the brake pedal 35 is connected to the right pedal shaft arm 756, and the link arm 761 projecting from the outer peripheral surface of the link boss body 760 has two stages. The lower end of the telescopic link body 769 is connected. When the brake operation shaft 757 is rotated according to the depression of the brake pedal 35, the two-stage telescopic link body 769 acts, so that the amount of depression for adjusting the traveling speed is small (play area of the brake mechanism 751). Thus, when the amount of stepping on the sudden brake is large (braking region by the brake mechanism 751), the depression force on the brake pedal 35 increases.

  The parking brake lever 43 is connected to one end of the locking member 771 via the parking brake arm 770. The locking member 771 having an arcuate side view is fixed to the brake pedal support bracket 916. On the left side surface of the pedal arm 35b of the brake pedal 35, a locking plate 775 that is engaged with the locking claw of the locking member 771 is provided. Thus, by operating the parking brake lever 43 with the brake pedal 35 depressed, the locking member 771 is locked to the locking plate 775, and the braking state (parking state) of the tractor 1 is maintained.

  Next, the internal structure of the straight traveling mission case 17 and the turning mission case 13 and the power transmission system of the tractor 1 will be described mainly with reference to FIGS. 4 to 6 and FIGS. In the front chamber of the straight traveling case 17, there are a hydraulic mechanical continuously variable transmission 500 for straight traveling, a mechanical creep transmission gear mechanism 502 for shifting rotational power via a forward / reverse switching mechanism 501, which will be described later, and a traveling auxiliary gear. A transmission gear mechanism 503 is disposed. A forward / reverse switching mechanism 501 that switches the rotational power from the hydraulic mechanical continuously variable transmission 500 in the forward or reverse direction is disposed in the intermediate chamber of the transmission case 17 for straight travel. A PTO transmission mechanism 505 that appropriately changes the rotational power from the engine 5 and transmits it to the PTO shaft 25 is disposed in the rear chamber of the straight traveling mission case 17. A pump case 480 accommodating a working machine hydraulic pump 481 driven by the rotational power of the engine 5 and a traveling hydraulic pump 482 is attached to the front part of the right outer surface of the straight traveling case 17.

  The straight traveling mission case 17 includes a forward / reverse switching mechanism 501 that is a part of the straight traveling clutch mechanism. That is, by setting the forward / reverse switching mechanism 501 to be neutral, the transmission of rotational power from the hydraulic mechanical continuously variable transmission 500 to the subsequent creep transmission gear mechanism 502 and the traveling auxiliary transmission gear mechanism 503 is stopped. The creep transmission gear mechanism 502 and the traveling auxiliary transmission gear mechanism 503 are a part of the straight traveling clutch mechanism, and correspond to a traveling transmission gear mechanism that performs multi-stage shifting of the transmission output via the forward / reverse switching mechanism 501.

  A flywheel 26 is directly connected to an output shaft 5a of the engine 5 that protrudes rearward from the rear side surface of the engine 5. An input counter shaft 28 projecting forward from the front side of the straight traveling mission case 17 is connected to a main driving shaft 27 projecting rearward from the flywheel 26 through a power transmission shaft 29 having universal joints at both ends. The rotational power of the engine 5 is transmitted to the input counter shaft 28 of the straight traveling mission case 17 via the main driving shaft 27 and the power transmission shaft 29, and the hydraulic mechanical continuously variable transmission 500 and the creep transmission gear mechanism 502 or the traveling auxiliary gear The speed is appropriately changed by the transmission gear mechanism 503. The shifting power via the creep transmission gear mechanism 502 or the traveling auxiliary transmission gear mechanism 503 is transferred to the gear mechanism in the turning mission case 13 via the linear output shaft 30, the power transmission shaft 31, and the linear input counter shaft 508. Communicated.

  In a straight-forward hydraulic mechanical continuously variable transmission (HMT) 500, a main transmission output shaft 512 is concentrically disposed on a main transmission input shaft 511, and a hydraulic pump unit 521, a cylinder block, and a hydraulic motor unit 522 are arranged in series. Are in-line type (in-line type). A main transmission input gear 513 is fitted on the rear end side of the input counter shaft 28 so as not to be relatively rotatable. An input transmission gear 514 that is always meshed with the main transmission input gear 513 is fixed to the rear end side of the main transmission input shaft 511. Accordingly, the rotational power of the input counter shaft 28 is transmitted to the hydraulic mechanical continuously variable transmission 500 via the main transmission input gear 513, the input transmission gear 514, and the main transmission input shaft 511. A main transmission high-speed gear 516, a main transmission reverse gear 517, and a main transmission low-speed gear 515 are fitted on the main transmission output shaft 512 so as not to rotate relative to each other for traveling output. The input side of the main transmission input shaft 511 and the output side of the main transmission output shaft 512 are located on the same side (both rear as viewed from the hydraulic mechanical continuously variable transmission 500).

  The hydraulic mechanical continuously variable transmission 500 includes a variable displacement hydraulic pump unit 521 and a constant displacement hydraulic motor unit 522 that is operated by high-pressure hydraulic oil discharged from the hydraulic pump unit 521. The hydraulic pump unit 521 is provided with a pump swash plate 523 that can change the inclination angle with respect to the axis of the main transmission input shaft 511 and adjust the amount of hydraulic oil supplied. A main transmission hydraulic cylinder 524 that changes and adjusts the inclination angle of the pump swash plate 523 with respect to the axis of the main transmission input shaft 511 is linked to the pump swash plate 523. In the embodiment, the main transmission hydraulic cylinder 524 is assembled to the hydraulic mechanical continuously variable transmission 500 and unitized as one member.

  When the main transmission hydraulic cylinder 524 is driven in proportion to the operation amount of the main transmission lever 50, the inclination angle of the pump swash plate 523 with respect to the axis of the main transmission input shaft 511 is changed accordingly. The pump swash plate 523 of the embodiment is angle-adjusted in a range between one (positive) maximum inclination angle and the other (negative) maximum inclination angle with a neutral angle of substantially zero inclination (before and after including zero) interposed therebetween. It is possible to set an angle that is inclined to one of the two times when the vehicle speed of the traveling machine body 2 is the lowest (in this case, an inclination angle that is negative and near the maximum).

  When the inclination angle of the pump swash plate 523 is substantially zero (neutral angle), the hydraulic pump unit 521 does not push and pull the input side plunger group. Although the cylinder block rotates in the same direction and substantially the same rotational speed as the main transmission input shaft 511, there is no hydraulic oil supply from the hydraulic pump unit 521, so the output side plunger group of the cylinder block and thus the hydraulic motor unit 522 are not driven. The main transmission output shaft 512 rotates at substantially the same rotational speed as the main transmission input shaft 511.

  Next, a forward / backward switching structure executed via the forward / reverse switching mechanism 501 will be described. A planetary gear mechanism 526 that is a forward high-speed gear mechanism and a low-speed gear pair 525 that is a forward low-speed gear mechanism are disposed on the rear side of the input counter shaft 28. The planetary gear mechanism 526 includes a sun gear 531 that rotates integrally with an input-side transmission gear 529 that is rotatably supported on the input counter shaft 28, a carrier 532 that rotatably supports a plurality of planetary gears 533 on the same radius, In addition, a ring gear 534 having internal teeth on the inner peripheral surface is provided. The sun gear 531 and the ring gear 534 are rotatably fitted on the input counter shaft 28. The carrier 532 is fitted on the input counter shaft 28 so as not to be relatively rotatable. The sun gear 531 meshes with each planetary gear 533 of the carrier 532 from the inside of the radius. Further, the inner teeth of the ring gear 534 mesh with the planetary gears 533 from the radially outer side. An output side transmission gear 530 that rotates integrally with the ring gear 534 is also rotatably supported on the input counter shaft 28. The input-side low-speed gear 527 and the output-side low-speed gear 528 constituting the low-speed gear pair 525 are integrated, and can rotate between the planetary gear mechanism 526 and the main transmission input gear 513 in the input counter shaft 28. It is pivotally supported.

  In the straight traveling mission case 17, an input counter shaft 28, a main transmission input shaft 511, and a traveling relay shaft 535 extending in parallel with the main transmission output shaft 512 and a traveling transmission shaft 536 are arranged. A forward / reverse switching mechanism 501 is provided on a travel relay shaft 535 serving as a transmission shaft. That is, the traveling relay shaft 535 has a forward high-speed gear 540 coupled by a wet multi-plate forward high-speed hydraulic clutch 539, a reverse gear 542 coupled by a wet multi-plate reverse hydraulic clutch 541, and a wet multi-plate. A forward low-speed gear 538 connected by a forward low-speed hydraulic clutch 537 of the mold is fitted. A travel relay gear 543 is fitted between the forward high speed hydraulic clutch 539 and the reverse gear 542 in the travel relay shaft 535 so as not to be relatively rotatable. A travel transmission gear 544 that always meshes with the travel relay gear 543 is fitted to the travel transmission shaft 536 so as not to be relatively rotatable. The main transmission low speed gear 515 of the main transmission output shaft 512 is always meshed with the input low speed gear 527 of the low speed gear pair 525 on the input counter shaft 28 side, and the output low speed gear 528 is always meshed with the forward low speed gear 538. The main transmission high speed gear 516 of the main transmission output shaft 512 is always meshed with the input transmission gear 529 of the planetary gear mechanism 526 on the input counter shaft 28 side, and the output transmission gear 530 is always meshed with the forward high speed gear 540. A main transmission reverse gear 517 of the main transmission output shaft 512 is always meshed with the reverse gear 542.

  When the forward / reverse switching lever 36 is operated to the forward side, the forward low-speed hydraulic clutch 537 or the forward high-speed hydraulic clutch 539 is in a power connection state, and the forward low-speed gear 538 or forward high-speed gear 540 and the travel relay shaft 535 are connected to each other so as not to be relatively rotatable. Is done. As a result, forward low-speed or high-speed rotational power is transmitted from the main transmission output shaft 512 to the travel relay shaft 535 via the low-speed gear pair 525 or the planetary gear mechanism 526, and power is transmitted from the travel relay shaft 535 to the travel transmission shaft 536. Communicated. When the forward / reverse switching lever 36 is operated to the reverse side, the reverse hydraulic clutch 541 enters a power connection state, and the reverse gear 542 and the travel relay shaft 535 are coupled so as not to be relatively rotatable. As a result, the reverse rotational power is transmitted from the main transmission output shaft 512 to the traveling relay shaft 535 via the main transmission reverse gear 517 and the reverse gear 542, and the motive power is transmitted from the traveling relay shaft 535 to the traveling transmission shaft 536.

  Note that which of the forward low-speed hydraulic clutch 537 and the forward high-speed hydraulic clutch 539 is in the power connection state by the forward operation of the forward / reverse switching lever 36 is determined according to the operation amount of the main transmission lever 50. When the forward / reverse switching lever 36 is in the neutral position, all the hydraulic clutches 537, 539, and 541 are in the power cut state, and the traveling drive force from the main transmission output shaft 512 is substantially zero (the main clutch disengaged state). )become. Here, FIG. 10 shows the relationship between the hydraulic oil discharge amount (inclination angle of the pump swash plate 523) of the hydraulic mechanical continuously variable transmission 500 and the vehicle speed of the tractor 1. In the embodiment, when the main speed change lever 50 is neutrally operated regardless of the operating state of the forward / reverse switching lever 36, the pump swash plate 523 is negative and has an inclination angle near the maximum (reverse rotation inclination) by driving the main speed change hydraulic cylinder 524. (See white circles), the main transmission output shaft 512 and the travel relay shaft 535 are in the lowest speed rotation state (substantially zero). As a result, the vehicle speed of the tractor 1 becomes substantially zero.

  When the main transmission lever 50 is operated from the neutral to the intermediate speed while the forward / reverse switching lever 36 is operated to the forward side, the pump swash plate 523 is negative and maximum when the main transmission hydraulic cylinder 524 is driven. It changes from a nearby inclination angle (reverse rotation inclination angle) through zero to a positive and maximum vicinity inclination angle (forward rotation inclination angle) (see white squares), and from the hydraulic motor unit 522 to the main transmission output shaft 512. The speed change power is increased from approximately zero to high speed. At this time, the forward low-speed hydraulic clutch 537 is in a power connection state, and the forward low-speed gear 538 or the forward high-speed gear 540 and the travel relay shaft 535 are connected so as not to be relatively rotatable. As a result, the forward low-speed rotational power is transmitted from the main transmission output shaft 512 to the traveling relay shaft 535 via the low-speed gear pair 525, and the traveling relay shaft 535 is rotated at the lowest speed by the increased power to the main transmission output shaft 512. It changes from the state to the forward intermediate speed rotation state (refer to the forward low speed region FL). Then, power is transmitted from the travel relay shaft 535 to the travel transmission shaft 536.

  When the main transmission lever 50 is operated from the intermediate speed to the maximum speed while the forward / reverse switching lever 36 is operated to the forward side, the inclination angle is positive and near the maximum by driving the main transmission hydraulic cylinder 524. (Forward rotation tilt angle) changes from zero to a negative and maximum tilt angle (reverse rotation tilt angle) through zero, and the pump swash plate 523 shifts the shift power from the hydraulic motor unit 522 to the main shift output shaft 512 from a high speed. Decelerate to almost zero. At this time, the forward high speed hydraulic clutch 539 is in a power connection state, and the forward high speed gear 540 and the travel relay shaft 535 are coupled so as not to be relatively rotatable. As a result, forward high speed rotational power is transmitted from the main transmission output shaft 512 to the travel relay shaft 535 via the planetary gear mechanism 526. That is, after the power from the engine 5 and the deceleration power to the main transmission output shaft 512 are combined in the planetary gear mechanism 526, the travel relay shaft 535 is moved from the forward intermediate speed rotation state to the forward maximum speed rotation state by the combined power. Change (see forward high speed range FH). Then, power is transmitted from the travel relay shaft 535 to the travel transmission shaft 536. The traveling machine body 2 has the highest speed.

  When the main transmission lever 50 is operated from the neutral side to the acceleration side while the forward / reverse switching lever 36 is operated to the reverse side, the pump swash plate 523 is negative by the drive of the main transmission hydraulic cylinder 524 and the inclination angle near the maximum is reached. It changes from (reverse rotation tilt angle) to a positive and near-maximum tilt angle (forward rotation tilt angle) through zero, and the shift power from the hydraulic motor unit 522 to the main shift output shaft 512 is increased from substantially zero to high speed. Let At this time, the reverse hydraulic clutch 541 is in a power connection state, and the reverse gear 542 and the travel relay shaft 535 are coupled so as not to be relatively rotatable. As a result, the reverse rotational power is transmitted from the main transmission output shaft 512 to the traveling relay shaft 535 via the main transmission reverse gear 517 and the reverse gear 542, and the traveling relay shaft 535 is driven by the increased power to the main transmission output shaft 512. Changes from the lowest speed rotation state to the reverse high speed rotation state (see reverse region R). Then, power is transmitted from the travel relay shaft 535 to the travel transmission shaft 536.

  Next, an ultra-low speed, low-speed and high-speed switching structure executed through the creep transmission gear mechanism 502 and the traveling auxiliary transmission gear mechanism 503, which are traveling transmission gear mechanisms, will be described. In the straight transmission case 17, a mechanical creep transmission gear mechanism 502 and a traveling auxiliary transmission gear mechanism 503 for shifting rotational power via the forward / reverse switching mechanism 501, and a traveling counter that extends coaxially with the traveling transmission shaft 536. A shaft 545 and an auxiliary transmission shaft 546 extending in parallel with the travel counter shaft 545 are disposed.

  A transmission gear 547 and a creep gear 548 are provided on the rear side of the travel counter shaft 545. The transmission gear 547 is rotatably fitted to the travel counter shaft 545 and connected to the travel transmission shaft 536 so as to rotate integrally. The creep gear 548 is rotatably fitted on the travel counter shaft 545. A creep shifter 549 is spline-fitted between the transmission gear 547 and the creep gear 548 of the travel counter shaft 545 so as not to be relatively rotatable and slidable in the axial direction. The creep shifter 549 slides by turning the ultra low speed lever 44 on and off, and the transmission gear 547 and the creep gear 548 are alternatively connected to the travel counter shaft 545. A reduction gear pair 550 is rotatably fitted to a portion of the auxiliary transmission shaft 546 in the front chamber. The input side reduction gear 551 and the output side reduction gear 552 constituting the reduction gear pair 550 have an integral structure, and the transmission gear 547 of the travel counter shaft 545 always meshes with the input side reduction gear 551 of the auxiliary transmission shaft 546, The creep gear 548 is always meshed with the output side reduction gear 552.

  A low speed relay gear 553 and a high speed relay gear 554 are provided on the front side of the travel counter shaft 545. The low speed relay gear 553 is fixed to the travel counter shaft 545. The high-speed relay gear 554 is fitted on the travel counter shaft 545 so as not to be relatively rotatable. A low-speed gear 555 that meshes with the low-speed relay gear 553 and a high-speed gear 556 that meshes with the high-speed relay gear 554 are rotatably fitted on the auxiliary transmission shaft 546 on the front side of the reduction gear pair 550. A sub-transmission shifter 557 is spline-fitted between the low-speed gear 555 and the high-speed gear 556 in the sub-transmission shaft 546 so as not to be relatively rotatable and slidable in the axial direction. By operating the sub transmission lever 45, the sub transmission shifter 557 slides and the low speed gear 555 and the high speed gear 556 are alternatively connected to the sub transmission shaft 546. An intermediate position between the low speed gear 555 and the high speed gear 556 is a sub shift neutral position where the low speed gear 555 and the high speed gear 556 are not connected to the sub shift shifter 557.

  Further, a straight traveling relay shaft 568 and a straight traveling output shaft 30 that extend in parallel with the travel counter shaft 545 and the auxiliary transmission shaft 546 are arranged. The driven gear 569 fitted so as to be relatively non-rotatable with the straight-traveling relay shaft 568 is always meshed with the main driving gear 569 fitted so as not to be relatively rotatable on the front end side of the auxiliary transmission shaft 546. A straight travel relay gear 582 that is fitted to the rear end side of the straight travel relay shaft 568 so as not to be relatively rotatable, and a straight travel output gear 583 that is fitted to the straight travel output shaft 30 so as not to be relatively rotatable are always meshed.

  The main drive gear 569 of the subtransmission shaft 546, the driven gear 570 and the rectilinear relay gear 582 of the rectilinear relay shaft 568, and the rectilinear output gear 583 of the rectilinear output shaft 30 are used to linearly rotate the subtransmission shaft 456. A straight output gear mechanism 509 for transmitting power to the output shaft 30 is configured. The straight output gear mechanism 509 is provided with a straight pickup pickup rotation sensor (straight vehicle speed sensor) 823, and the straight pickup pickup rotation sensor 823 detects the rotational speed (straight vehicle speed) of the straight output. For example, the straight traveling relay gear 582 is disposed so as to face the straight traveling pickup rotation sensor 823, and the rotational speed of the straight traveling output (straight traveling vehicle speed) is detected from the rotational speed of the straight traveling relay gear 582.

  In the embodiment, when the super low speed lever 44 is turned on and the sub transmission lever 45 is operated to the low speed side, the creep gear 548 is connected to the travel counter shaft 545 so as not to be relatively rotatable, and the low speed gear 555 is connected to the sub transmission shaft 546. A traveling driving force that is coupled so as not to be relatively rotatable and that is ultra-low speed than the straight output shaft 30 is output toward the turning mission case 13. When the super low speed lever 44 is turned off and the sub transmission lever 45 is operated to the low speed side, the transmission gear 547 is connected to the travel counter shaft 545 so as not to rotate relative to it, and the low speed gear 555 cannot be rotated relative to the sub transmission shaft 546. The traveling drive force at an extremely low speed is output from the straight output shaft 30 toward the turning mission case 13. When the super low speed lever 44 is turned off and the sub transmission lever 45 is operated to the high speed side, the transmission gear 547 is connected to the travel counter shaft 545 so as not to rotate relative to it, and the high speed gear 556 cannot be rotated relative to the sub transmission shaft 546. The traveling drive force at a higher speed than the straight traveling output shaft 30 is output toward the turning mission case 13. Further, when the auxiliary transmission lever 45 is operated to the neutral position, the auxiliary transmission shaft 546 is disconnected from the low speed gear 555 and the high speed gear 556, and the power from the traveling transmission shaft 536 is cut off by the traveling auxiliary transmission gear mechanism 503. .

  The turning mission case 13 includes a turning hydraulic continuously variable transmission (HST) 701 for appropriately changing the rotational power from the engine 5, and an output rotation from the hydraulic continuously variable transmission 701 to the left and right traveling crawlers 3 ( A differential gear mechanism 702 for transmitting to the drive sprocket 62), and a pair of left and right planetary gear mechanisms 703 for synthesizing the rotational power from the differential gear mechanism 702 and the rotational power from the straight traveling mission case 17. Also, a linear input counter shaft 508 that protrudes backward from the turning mission case 13 and a linear output shaft 30 that protrudes forward from the lower front portion of the linear transmission case 17 are connected by a power transmission shaft 31. .

  In the hydraulic continuously variable transmission 701, a pair of hydraulic pump units 704 and a hydraulic motor unit 705 are arranged in parallel, and the power transmitted to the pump shaft 706 is transferred from the hydraulic pump unit 704 to the hydraulic motor unit 705. The hydraulic oil is fed appropriately. A charge pump 707 for supplying hydraulic oil to the hydraulic pump unit 704 and the hydraulic motor unit 705 is attached to the pump shaft 706. The turning hydraulic continuously variable transmission 701 changes the discharge angle and discharge amount of the hydraulic oil to the hydraulic motor unit 705 by changing and adjusting the inclination angle of the pump swash plate 708 in the hydraulic pump unit 704, thereby changing the hydraulic pressure. The motor shaft 709 protruding from the motor unit 705 is configured to arbitrarily adjust the rotation direction and the number of rotations.

  The pump shaft 706 of the hydraulic continuously variable transmission 701 is connected to the output side (front side) of the turning clutch mechanism 300, and the clutch input shaft 301 is connected to the input side (rear side) of the turning clutch mechanism 300. It is connected. The turning shifter 302 for connecting and disconnecting the turning clutch mechanism 300 is displaced by the electric actuator 303 installed in the turning mission case 13. That is, when the turning shifter 302 is displaced along the clutch input shaft 301 by the electric actuator 303, the turning clutch mechanism 300 is connected and disconnected, and the clutch input shaft 301 and the pump shaft 706 are connected or disconnected.

  In the turning mission case 13, the turning input counter shaft 712 is disposed in parallel with the clutch input shaft 301, and the turning input gear 713 is fitted on the turning input counter shaft 712 so as not to be relatively rotatable. A turning relay shaft 714 is disposed between the turning input counter shaft 712 and the clutch input shaft 301 in parallel with the turning input counter shaft 712 and the clutch input shaft 301, and is always meshed with the turning input gear 713. The turning relay gear 715 is fitted to the turning relay shaft 714 so as not to be relatively rotatable. The clutch input shaft 301 is fitted with a pump input gear 710 that is always meshed with the turning relay gear 715 so as not to be relatively rotatable, and the rotational power transmitted from the engine 5 transmitted to the turning input counter shaft 712 is This is transmitted to the clutch input shaft 301 via the turning relay shaft 714.

  In the turning mission case 13, a differential gear mechanism 702 is configured by a bevel gear mechanism in which a pair of left and right side gears 717 are engaged with both sides of a pinion gear 716 that is fitted to the rear end of the motor shaft 709 so as not to be relatively rotatable. Yes. In addition, the differential gear mechanism 702 has a pair of left and right turning output shafts 718 each having a side gear 717 fitted at one end thereof so as not to rotate relative to each other. A turning output gear 719 for transmitting power to the pair of left and right planetary gear mechanisms 703 is fitted to the other end of each of the pair of left and right turning output shafts 718 so as not to be relatively rotatable.

  Rotational power (turning rotational power) from the hydraulic motor unit 705 output from the motor shaft 709 is branched into forward and reverse rotational power by the differential gear mechanism 702 and left and right via a pair of left and right turning output shafts 718. This is transmitted to the pair of planetary gear mechanisms 703. That is, in the differential gear mechanism 702, the reverse rotation power is transmitted to the left planetary gear mechanism 703 through the left turning output shaft 718 fitted with the left side gear 717, while the right side gear 717 is fitted. It is transmitted to the right planetary gear mechanism 703 as forward rotation power through the right turning output shaft 718.

  The hydraulic motor unit 705 of the turning hydraulic continuously variable transmission 701 is provided with a turning pickup rotation sensor (turning vehicle speed sensor) 824, and the turning pickup rotation sensor 824 detects the rotation speed (turning vehicle speed) of the turning output. It is configured to do. In the present embodiment, a turning pulse generating rotating wheel 738 is provided on the motor shaft 709, and a turning pickup rotation sensor 824 is arranged to face the turning pulse generating rotating wheel 738, so that a turning pulse generating rotating wheel is obtained. Based on the rotational speed of 738, the rotational speed (turning vehicle speed) of the straight-ahead output is detected.

  In the turning mission case 13, a rectilinear brake mechanism 751 that interlocks with the operation of the brake pedal 35 is provided on the rectilinear input counter shaft 508 to which the rotational power from the rectilinear mission case 17 is transmitted. Then, the linear input gear 720 is fitted to the front end of the linear input counter shaft 508 so as not to be relatively rotatable. Further, the straight travel relay shaft 721 is arranged in parallel with the straight travel input counter shaft 508, and the straight travel relay gear 722 that is always meshed with the straight travel input gear 720 is not rotatable relative to the straight travel relay shaft 721. It is fitted.

  A bevel gear mechanism is provided in which a ring gear 724 is engaged with a pinion gear 723 that is fitted to the rear end of the linear relay shaft 721 so as not to be relatively rotatable. The ring gear 724 cannot be relatively rotated on a straight output shaft 725 that is extended to the left and right. It is put on. Both ends of the straight output shaft 725 are connected to a pair of left and right planetary gear mechanisms 703, respectively. The rotational power (straight forward rotational power) from the straight traveling mission case 17 input to the straight traveling input counter shaft 508 is transmitted to the pair of left and right planetary gear mechanisms 703 via the straight traveling output shaft 725. In addition, the linear brake mechanism 751 performs a braking operation according to the operation of the brake pedal 35, so that the rotational power of the linear output shaft 725 is attenuated or stopped.

  The left and right planetary gear mechanisms 703 rotate one sun gear 726, a plurality of planet gears 727 meshed with the sun gear 726, a ring gear 728 meshed with the turning output gear 719, and a plurality of planet gears 727 on the same circumference. And a carrier 729 which can be arranged. The carriers 729 of the left and right planetary gear mechanisms 703 are arranged on the same axis so as to face each other with an appropriate interval. The left and right sun gears 726 are fixed to both ends of a straight output shaft 725 in which a ring gear 724 is fitted in the middle.

  The left and right ring gears 728 are rotatably fitted to the straight output shaft 725, and the external teeth on the outer peripheral surface thereof are engaged with the left and right turning output gears 719 to be connected to the turning output shaft 718. ing. A carrier 729 fixed to the ring gear 728 rotatably supports the planetary gear 727. The left and right carriers 729 are rotatably fitted to the left and right differential output shafts 730. The left and right output transmission gears 731 that rotate together with the left and right planetary gears 727 mesh with the left and right differential input gears 732 that are non-rotatably fitted to the left and right differential output shafts 730. doing. The left and right differential output shafts 730 are connected to the left and right relay shafts 735 via relay gears 733 and 734, and the left and right relay shafts 735 are connected to the left and right axles 16 via final gears 736 and 737. ing.

  Each of the left and right planetary gear mechanisms 703 receives rotational power from the straight traveling mission case 17 via the straight traveling relay shaft 721 and the straight traveling output shaft 725, and rotates the sun gear 726 at the same rotational speed in the same direction. . That is, the left and right sun gears 726 receive the rotational power from the straight traveling mission case 17 as straight traveling rotation, and transmit it to the differential output shaft 730 through the planetary gear 727 and the output side transmission gear 731. Therefore, the rotational power transmitted from the straight traveling mission case 17 to the left and right planetary gear mechanisms 703 is transmitted from the left and right axles 16 to the drive sprockets 62 at the same rotational speed in the same direction, and the left and right traveling crawlers 3 are transmitted to the same. Driven at the same rotational speed in the direction, the traveling machine body 2 is moved straight (forward, backward).

  On the other hand, the left and right planetary gear mechanisms 703 receive rotational power from the hydraulic motor unit 705 via the differential gear mechanism 702 and the turning output shaft 718, and cause the ring gear 728 to rotate in the opposite directions at the same rotational speed. Rotate. In other words, the left and right ring gears 728 receive the rotational power from the hydraulic motor unit 705 as turning rotation, and the carrier 729 causes the turning rotation to be superimposed on the straight rotation from the sun gear 726 to rotate the planetary gear 727 and the output side transmission gear 731. . As a result, the rotational power obtained by adding the turning rotation to the straight rotation is transmitted to one of the left and right differential output shafts 730 via the planetary gear 727 and the output side transmission gear 731. Rotational power obtained by subtracting the turning rotation from the straight rotation is transmitted to the other of the two via the planetary gear 727 and the output side transmission gear 731.

  The speed change outputs from the linear input counter shaft 508 and the motor shaft 709 are transmitted to the drive sprockets 62 of the left and right traveling crawlers 3 via the left and right planetary gear mechanisms 703, respectively, so that the vehicle speed (traveling speed) of the traveling machine body 2 is increased. ) And the direction of travel is determined. That is, when the rotational power from the straight traveling mission case 17 is input to the straight traveling input counter shaft 508 with the hydraulic motor portion 705 of the hydraulic continuously variable transmission 701 stopped and the left and right ring gears 728 stationary and fixed. The rotation of the straight traveling input counter shaft 508 is transmitted to the left and right sun gears 726 at the same left and right rotational speed, the left and right traveling crawlers 3 are driven at the same rotational speed in the same direction, and the traveling machine body 2 travels straight.

  Conversely, when the hydraulic motor unit 705 of the hydraulic continuously variable transmission 701 is driven in a state where the rotation of the transmission case 17 for the straight traveling is stopped by the straight output shaft 30 and the left and right sun gears 726 are stationary and fixed, the motor shaft 709 is driven. Rotational power from the left ring gear 728 rotates forward (reverse), and the right ring gear 728 rotates reverse (forward). As a result, one of the drive sprockets 62 of the left and right traveling crawlers 3 is rotated forward, the other is rotated backward, and the traveling machine body 2 is turned on the spot (revolution turning spin turn).

  Further, the left and right traveling crawlers 3 are driven by driving the left and right ring gears 728 by turning the hydraulic motor portion 705 of the hydraulic continuously variable transmission 701 while driving the left and right sun gears 726 by rotating straight from the transmission case 17 for straight traveling. The traveling body 2 turns left or right (U-turn) with a turning radius larger than the belief turning radius while moving forward or backward. The turning radius at this time is determined according to the speed difference between the left and right traveling crawlers 3.

  Next, the drive speed switching structure (three forward rotations and one reverse rotation) of the PTO shaft 25 executed via the PTO transmission mechanism 505 will be described. The straight traveling mission case 17 is provided with a PTO transmission mechanism 505 that transmits power from the engine 5 to the PTO shaft 25. In this case, a PTO input shaft 591 extending coaxially with the main transmission input shaft 511 is connected to the rear end side of the main transmission input shaft 511 via a PTO hydraulic clutch 590 for power transmission interruption. Further, the straight traveling mission case 17 is provided with a PTO transmission shaft 592, a PTO counter shaft 593, and a PTO shaft 25 extending in parallel with the PTO input shaft 591. The PTO shaft 25 protrudes rearward from the rear surface of the straight traveling mission case 17.

  When the power connection operation is performed on the PTO clutch switch 53, the PTO hydraulic clutch 590 is in a power connection state, and the main transmission input shaft 511 and the PTO input shaft 591 are coupled so as not to be relatively rotatable. As a result, rotational power is transmitted from the main transmission input shaft 511 toward the PTO input shaft 591. The PTO input shaft 591 is provided with a plurality of speed change input gears and a reverse input gear, the PTO speed change shaft 592 is provided with a plurality of speed change gears and a PTO transmission gear, and the PTO counter shaft 593 is provided with A PTO relay gear, a PTO reverse gear, and a PTO output gear are provided.

  When the PTO shift lever 46 is shifted, the PTO shift shifter slides along the PTO shift shaft 592 and one of the plurality of shift gears is selectively connected to the PTO shift shaft 592. As a result, the PTO shift output is transmitted from the PTO shift shaft 592 to the PTO shaft 25 via the PTO counter shaft 593. When the sub PTO lever 48 is turned on and operated, the reverse input gear (reverse shifter gear) meshes with the PTO reverse gear of the PTO counter shaft, and the rotational power of the PTO input shaft 591 is transmitted to the PTO shaft 25 via the PTO counter shaft 593. The

  As described above, the tractor 1 of this embodiment is provided with the turning clutch mechanism 300 between the engine 5 and the turning hydraulic continuously variable transmission 701. On the other hand, between the planetary gear mechanism 703 serving as a power combining mechanism and the straight-forward hydraulic mechanical continuously variable transmission 500, the vehicle travels straight by the forward / reverse switching mechanism 501, the creep transmission gear mechanism 502, the traveling auxiliary transmission gear mechanism 503, and the like. A clutch mechanism is provided.

  Therefore, the transmission of power transmission from the engine 5 to the hydraulic continuously variable transmission 701 and the transmission of power transmission from the hydraulic mechanical continuously variable transmission machine 500 are controlled independently of each other. It is possible to optimally control the turning operation and the straight operation of the airframe 2. In other words, even when an abnormality occurs in either the straight-traveling hydraulic mechanical continuously variable transmission 500 or the turning hydraulic continuously variable transmission 701 and an emergency stop is caused, each hydraulic mechanical continuously variable transmission The power transmission at 500 and 701 can be cut off, and the tractor 1 can be safely stopped.

  Further, even when the pump swash plate 708 of the turning hydraulic continuously variable transmission 701 is tilted when the engine 5 is started, the power transmission to the hydraulic continuously variable transmission 701 is cut off. The output from the hydraulic continuously variable transmission 701 can be stopped to prevent an unexpected turning operation. Furthermore, when the viscosity of the hydraulic oil is high, such as when the engine 5 is started at a low temperature, the load on the engine 5 is reduced by releasing the connection between the hydraulic continuously variable transmission 701 and the engine 5. 5 can be started smoothly.

  Next, the hydraulic circuit 620 structure of the tractor 1 will be described with reference to FIG. The hydraulic circuit 620 of the tractor 1 includes a working machine hydraulic pump 481 and a traveling hydraulic pump 482 that are driven by the rotational power of the engine 5. In the embodiment, the straight traveling mission case 17 is used as a working oil tank, and the working oil in the straight traveling mission case 17 is supplied to the working machine hydraulic pump 481 and the traveling hydraulic pump 482. The traveling hydraulic pump 482 is connected to a closed loop oil passage 623 that connects the hydraulic pump unit 521 and the hydraulic motor unit 522 in the straight-traveling hydraulic mechanical continuously variable transmission 500. While the engine 5 is being driven, the hydraulic oil from the traveling hydraulic pump 482 is always replenished to the closed loop oil passage 623.

  The traveling hydraulic pump 482 includes a main transmission hydraulic pressure switching valve 624 for the main transmission hydraulic cylinder 524 of the hydraulic mechanical continuously variable transmission 500, a PTO clutch electromagnetic valve 627 for the PTO hydraulic clutch 590, and a switching valve 628 operated thereby. And connected to. Further, the traveling hydraulic pump 482 includes a forward low speed clutch electromagnetic valve 632 that operates the forward low speed hydraulic clutch 537, a forward high speed clutch electromagnetic valve 633 that operates the forward high speed hydraulic clutch 539, and a reverse clutch that operates the reverse hydraulic clutch 541. The solenoid valve 634 is connected to a master control solenoid valve 635 that controls the supply of hydraulic oil to the clutch solenoid valves 632 to 634.

  In addition, the work machine hydraulic pump 481 includes a plurality of hydraulic external take-off valves 430 arranged on the upper surface of the hydraulic lifting mechanism 22 on the rear side of the upper surface of the straight traveling mission case 17, and a hydraulic lift cylinder in the hydraulic lifting mechanism 22. 117 Double-action control solenoid valve 432 that controls the supply of hydraulic oil to the upper side, tilt control solenoid valve 647 that controls the supply of hydraulic oil to the horizontal cylinder 122 provided on the right lift rod 121, and hydraulic pressure in the hydraulic lifting mechanism 22 The rising hydraulic pressure switching valve 648 and the lowering hydraulic pressure switching valve 649 for controlling the hydraulic oil supply to the lower side of the lift cylinder 117, the rising control electromagnetic valve 650 for switching the rising hydraulic pressure switching valve 648, and the lowering hydraulic pressure switching valve 649 are operated. It is connected to the lowering control electromagnetic valve 651. The double-acting valve mechanism 431 includes a hydraulic circuit including a double-acting control electromagnetic valve 432, and the ascending / descending valve mechanism 652 includes an ascending hydraulic switching valve 648, a descending hydraulic switching valve 649, an ascending control electromagnetic valve 650, and a descending A hydraulic circuit including a control solenoid valve 651 is used.

  When the tilt control electromagnetic valve 647 is switched and driven, the horizontal cylinder 122 expands and contracts, and the right lower link 23 moves up and down with the lower link pin on the front side as a fulcrum. As a result, the ground work machine 18 tilts left and right with respect to the traveling machine body 2 via the left and right lower links 23, and the left and right tilt angles of the ground work machine 18 change. By switching control of the double-acting control electromagnetic valve 432, either a single-acting type or a double-acting type can be selected as a driving method of the hydraulic lift cylinder 117. In other words, the drive system of the hydraulic lift cylinder 117 is set by switching the double-action control electromagnetic valve 432 in accordance with the switching operation of the single-double action switch 56.

  When the hydraulic lift cylinder 117 is driven by a single action, when the rising hydraulic pressure switching valve 648 or the downward hydraulic pressure switching valve 649 is switched, the hydraulic lift cylinder 117 expands and contracts, and the lift arm 120 and both the left and right lower links 23 are both moved. Move up and down. As a result, the ground work machine 18 moves up and down, and the height position of the ground work machine 18 changes. On the other hand, when the hydraulic lift cylinder 117 is driven in a double-acting manner, the hydraulic lift cylinder 117 is expanded and contracted by switching the double-acting control electromagnetic valve 432 and simultaneously switching the upward hydraulic switching valve 648 or the downward hydraulic switching valve 649. Move. Accordingly, the ground work machine 18 can be moved up and down, and when the ground work machine 18 is lowered, the ground work machine 18 is pressurized toward the ground, and the ground work machine 18 can be held in the lowered position.

  The hydraulic circuit 620 of the tractor 1 includes a charge pump 707 that is driven by the rotational power of the engine 5, and the charge pump 707 includes a hydraulic pump unit 704 and a hydraulic motor unit 705 in the turning hydraulic continuously variable transmission 701. Is connected to a closed-loop oil passage 740 connecting the two. In the embodiment, the straight traveling mission case 17 is used as a hydraulic oil tank, and the hydraulic oil in the straight traveling mission case 17 is supplied to the charge pump 707 via an oil filter (suction filter) 743. During the driving of the engine 5, hydraulic oil from the charge pump 707 is always replenished to the closed loop oil passage 740 via the oil filter (line filter) 744. The hydraulic circuit 620 of the tractor 1 includes a swing hydraulic cylinder 741 that changes the angle of the pump swash plate 708 of the hydraulic pump unit 704 in the hydraulic continuously variable transmission 701, and a swing hydraulic pressure switching valve 742 for the swing hydraulic cylinder 741.

  The hydraulic circuit 620 of the tractor 1 includes a lubricating oil pump 518 that is driven by the rotational power of the engine 5 in addition to the aforementioned working machine hydraulic pump 481 and traveling hydraulic pump 482. The lubricating oil pump 518 includes a PTO clutch hydraulic pressure switching valve 641 that supplies hydraulic oil (lubricating oil) to the lubricating portion of the PTO hydraulic clutch 590, and a main transmission input shaft 511 that supports the hydraulic mechanical continuously variable transmission 500. The lubrication section, the forward low speed clutch hydraulic pressure switching valve 642 that supplies hydraulic oil (lubricating oil) to the lubrication section of the forward low speed hydraulic clutch 537, and the forward movement that supplies hydraulic oil (lubricating oil) to the lubrication section of the forward high speed hydraulic clutch 539. The high-speed clutch hydraulic pressure switching valve 643 is connected to a reverse clutch hydraulic pressure switching valve 644 that supplies hydraulic oil (lubricating oil) to the lubricating portion of the reverse hydraulic clutch 541. The hydraulic circuit 620 includes a relief valve, a flow rate adjustment valve, a check valve, an oil cooler, an oil filter, and the like.

  Next, the configuration around the turning mission case 13 will be described below with reference to FIGS. As shown in FIGS. 13 to 16, the turning mission case 13 includes a turning transmission case 91 incorporating a hydraulic continuously variable transmission 701, a relay case 92 including a turning clutch mechanism 300 and a motor shaft 709. The input / output case 93 includes a gear mechanism that receives rotational power from the engine 5 and the straight traveling mission case 17 and outputs rotational power to the axle 16. In the turning transmission case 91, a charge pump 707 is arranged on the front surface, and a turning hydraulic pressure switching valve 742 is arranged on the upper surface thereof. An input / output case 93 is connected to the rear of the turning transmission case 91 via a relay case 92, and an axle case 90 is connected to both sides of the input / output case 93.

  As shown in FIGS. 13 and 15, oil filters 743 and 744 are provided in front of the turning mission case 13. The oil filters 743 and 744 are suspended and fixed to a filter fixing bracket 459 installed on the left and right upper edges of the frame connecting member 12a that connects the front ends of the left and right engine frames 14. A partition plate 460 is provided above the turning mission case 13 so as to be installed on the left and right engine frames 14. The partition plate 460 is provided in front of the boundary position between the relay case 92 and the input / output case 93.

  A hydraulic pipe 450 that circulates hydraulic oil in the turning mission case 13 extends from the straight traveling mission case 17 toward the turning mission case 13. The hydraulic piping 450 on the straight traveling mission case 17 side is disposed along the traveling machine body 2 outside the traveling machine body 2 (the engine frame 14 and the machine frame 15). On the other hand, the hydraulic piping 450 on the turning mission case 13 side is disposed inside the traveling machine body 2 and connected to the turning mission case 13 via filters 743 and 744 provided inside the traveling machine body 2. A part is supported by the partition plate 460.

  As shown in FIGS. 15 to 19, the turning clutch mechanism 300 includes a main clutch 304 that connects an input side from the engine 5 and an output side to the hydraulic continuously variable transmission 701, and a connection of the main clutch 304. A shock-absorbing clutch 305 that relieves shock during operation is provided. The main clutch 304 is constituted by a meshing clutch (dog clutch), and the buffer clutch 305 is constituted by a friction clutch.

  With this configuration, when the turning clutch mechanism 300 is connected, the main clutch 304 can be connected after gradually transmitting the rotation on the input side to the output side by the buffer clutch 305. Therefore, it is possible to reduce the impact applied when the turning clutch mechanism 300 is connected, and to suppress the breakage and deterioration of the components of the turning clutch mechanism 300. In addition, since the power from the engine 5 is not suddenly transmitted to the hydraulic continuously variable transmission 701, it is possible to prevent a sudden turning operation when the turning clutch mechanism 300 is connected, and to improve safety during running. It can be secured. Further, when the turning clutch mechanism 300 is connected, the load from the hydraulic continuously variable transmission 701 is not abruptly applied to the engine 5, which not only prevents the engine 5 from stalling but also makes the engine 5 smoother. Can be started.

  The turning clutch mechanism 300 includes a clutch output shaft 306 connected to the pump shaft 706 and a clutch relay shaft 307 arranged concentrically with the clutch output shaft 306. The clutch input shaft 301 and the clutch output shaft 306 have a clutch input claw portion 308 and a clutch output claw portion 309 at opposite ends, respectively, and the main clutch 304 is connected to the clutch input claw portion 308 and the clutch output claw portion 309. Configure. The clutch relay shaft 307 is fitted on the clutch output shaft 306 via the thrust bearing 310 so as not to be relatively rotatable and to be slidable in the axial direction. As the clutch relay shaft 307 slides in the axial direction with respect to the clutch output shaft 306, the clutch input claw portion 308 and the clutch output claw portion 309 come in contact with each other, and the main clutch 304 is disconnected.

  Both ends of the clutch input shaft 301 are pivotally supported by an input / output case 93, and an insertion hole 311 is formed at the center of the front end where the clutch input claw 308 is provided. The front end of the clutch output shaft 306 is pivotally supported by the relay case 92, while the rear end thereof is inserted into the insertion hole 311 and is pivotally supported by the clutch input shaft 301 via the buffer clutch 305. The clutch output shaft 306 has a connecting hole 312 formed in the central portion of the front end thereof, and is connected to the pump shaft 706 inserted into the connecting hole 312 so as not to be relatively rotatable.

  The cylindrical clutch relay shaft 307 has a ring-shaped insertion groove 313 formed at the front end thereof and a plurality of springs 314 inserted therein, and a clutch output claw portion 309 protruding from the rear end thereof. The front ends of the plurality of springs 314 are fixed to a spring retaining ring 315 fixed to the rear end of the clutch output shaft 306, and the plurality of springs 314 are provided around the outer periphery of the clutch output shaft 306 so that the clutch relay shaft 307 is engaged with the clutch. It is biased toward the input shaft 301 side (rear side). A locking groove 316 is formed in the outer peripheral surface of the middle portion of the clutch relay shaft 307, and the tip of the turning shifter 302 is locked to the locking groove 316. When the turning shifter 302 moves in the front-rear direction, the clutch relay shaft 307 moves in conjunction with the clutch input shaft 301 and the clutch output shaft 306 in the axial direction.

  A step portion 317 is provided on the front side of the inner peripheral wall of the clutch relay shaft 307, and a spring retaining ring 318 is fixed by the step portion 317. The spring retaining ring 318 is fitted to the outer peripheral surface of the clutch output shaft 306 so as to be slidable in the axial direction, and the front end of the spring 319 fitted from the rear end of the clutch output shaft 306 is fixed. A pressing ring 320 fitted from the rear end of the clutch output shaft 306 is fixed to the rear end of the spring 319. That is, a spring 319 having a pressing ring 320 at the rear end is provided between the step 317 of the clutch relay shaft 307 and the buffer clutch 305. The spring 319 moves relative to the clutch input shaft 301 and the clutch output shaft 306 in the axial direction together with the clutch relay shaft 307 to bring the pressing ring 320 and the buffer clutch 305 into contact with each other, and the buffer clutch 305 is connected and disconnected.

  When the main clutch 304 and the buffer clutch 305 are both disconnected, the interval L1 between the front end of the clutch input shaft 301 and the rear end of the clutch relay shaft 307 is equal to the interval L2 between the front end of the buffer clutch 305 and the rear end of the pressure ring 320. Compared to wider. Accordingly, when the clutch relay shaft 307 is slid rearward by the turning shifter 302 when the turning clutch mechanism 300 is connected, the spring 319 and the pressing ring 320 are pushed by the clutch relay shaft 307. The buffer clutch 305 and the pressing ring 320 abut. In this way, after the buffer clutch 305 is connected, when the clutch relay shaft 307 is further slid back, the clutch output claw portion 309 of the clutch relay shaft 307 is moved to the clutch input claw portion 308 of the clutch input shaft 301. The main clutch 304 is connected by meshing.

  That is, when the turning clutch mechanism 300 is connected, first, the pressing ring 320 is brought into contact with the buffer clutch 305, so that the buffer clutch 305 is in a half-clutch state, and the rotation from the clutch input shaft 301 is rotated by the clutch output shaft 306. And transmitted to the clutch relay shaft 307. As the clutch relay shaft 307 approaches the clutch input shaft 301, the urging force of the spring 319 against the pressing ring 320 increases. As a result, the clutch output pawl 309 of the clutch relay shaft 307 is moved to the clutch input pawl portion of the clutch input shaft 301 while the rotational speeds of the clutch output shaft 306 and the clutch relay shaft 207 approach the rotational speed of the clutch input shaft 301. The main clutch 304 is connected by meshing with 308.

  The turning clutch mechanism 300 is provided with a turning brake mechanism 321 on the output side to the hydraulic continuously variable transmission 701. When the turning clutch mechanism 300 is disconnected, the turning brake mechanism 321 is hydraulically stepless. The input to the transmission 701 is braked. The turning brake mechanism 321 is fitted on the outer peripheral surface of the front end side of the clutch relay shaft 307, and moves in the axial direction together with the discharge of the clutch relay shaft 307, so that the step 322 provided on the inner wall surface of the relay case 92 Connect and separate.

  When the turning clutch mechanism 300 is in a disconnected state, the clutch relay shaft 307 is moved forward, and the turning brake mechanism 321 provided in front of the clutch relay shaft 307 is pressed against the step portion 322 of the relay case 92. Then, the rotation of the clutch relay shaft 307 is braked. That is, when the turning clutch mechanism 300 is disconnected, the rotation of the clutch output shaft 306 and the clutch relay shaft 307 is surely stopped by the braking action of the turning brake mechanism 321, so that the pump of the hydraulic continuously variable transmission 701 The rotation of the shaft 706 is stopped. Therefore, when the turning clutch mechanism 300 is disconnected, the rotation of the pump shaft 706 can be forcibly stopped regardless of the inclination of the pump swash plate 708 of the hydraulic continuously variable transmission 701, and the unexpected turning of the traveling machine body 2 can be performed. Can be prevented.

  The electric actuator (motor) 303 rotates the turning shifter 302 pivotally supported by the shifter control shaft 331 via the clutch position switching mechanism 330 to connect and disconnect the turning clutch mechanism 300. As shown in FIGS. 15, 19, and 20, when the clutch position switching mechanism 330 receives rotation from the electric actuator 303 by the input arm 332, the clutch position switching mechanism 330 rotates the cam 334 via the relay arm 333, thereby The rotation shifter 302 is rotated by displacing the roller 336 of the output arm 335 connected to the 331 and rotating the shifter control shaft 331.

  The electric actuator 303 is placed on the top surface of the casing 337 that fixes the clutch position switching mechanism 330, and the motor shaft 338 of the electric actuator 303 penetrates below the top panel of the casing 337 to input the electric actuator 303. It is connected to one end of the arm 332. The housing 337 is fixed to the top surface of the relay case 92. A projecting portion 339 protrudes downward from the other end of the input arm 332, and the projecting portion 339 is locked in a long hole 340 provided on one end side of the relay arm 333. The other end of the relay arm 333 is connected to a cam shaft 341 that is connected to a cam 334 provided on the lower side of the relay arm 333, and the cam shaft 341 is pivotally supported by a bearing portion 342 of the housing 337.

  The output arm 335 pivotally supports a roller 336 on the upper surface of one end thereof, and a shifter control shaft 331 is erected on the other end of the output arm 335 and rotates together with the turning shifter 302 about the shifter control shaft 331 as an axis. The base end side of the turning shifter 302 is connected to the middle of the shifter control shaft 331, and is pivotally supported by the relay case 92, so that the tip of the turning shifter 302 is moved in accordance with the rotation of the output arm 335. The clutch relay shaft 307 is slid in the front-rear direction by being displaced in the front-rear direction.

  When the motor shaft 338 of the electric actuator 303 is rotated, the relay arm 333 is rotated by the rotation of the input arm 332, so that the cam 334 connected to the lower end of the cam shaft 341 is rotated. At this time, the protrusion 339 of the relay arm 333 slides through the long hole 340 provided along the longitudinal direction of the relay arm 333. The rotation of the cam shaft 341 causes the roller 336 in contact with the outer peripheral surface of the cam 334 to be displaced. At this time, the output arm 335 pivotally supporting the roller 336 rotates about the shifter control shaft 331, thereby rotating the shifter control shaft 331 and displacing the tip of the turning shifter 302 in the front-rear direction. Accordingly, the turning shifter 302 is pushed in the front-rear direction by the turning shifter 302, and the turning clutch mechanism 300 is disconnected.

  Next, a configuration for executing the traveling control of the tractor 1 will be described with reference to FIGS. As shown in FIG. 21, the tractor 1 includes a work machine controller 810 that controls the state of the ground work machine 18, an engine controller 811 that controls the drive of the engine 5, and an operation display panel (meter panel) mounted on the dashboard 33. 39, a meter controller 812 that controls the display operation of 39, and a straight-ahead controller 813 and a turning controller 814 that control the speed of the traveling machine body 2 and the like.

  The controllers 810 to 814 and the operation monitor 55 are each a CPU for executing various arithmetic processes and controls, a ROM for storing control programs and data, a RAM for temporarily storing control programs and data, A timer for time measurement, an input / output interface, and the like are provided, and are connected to each other via a CAN communication bus 815 so as to communicate with each other. The controllers 810 to 814 are connected to the battery 817 via the power application key switch 816.

  Based on the control by the engine controller 811, in the engine 5, the fuel in the fuel tank is pumped to the common rail by the fuel pump and stored as high-pressure fuel in the common rail. The engine controller 811 controls the opening and closing (electronic control) of each fuel injection valve so that the high-pressure fuel in the common rail (not shown) can accurately control the injection pressure, the injection timing, and the injection period (injection amount). After being controlled, each injector (not shown) is injected into each cylinder of the engine 5. Further, a cooling water temperature sensor 846 for detecting the cooling water temperature of the engine 5 and an engine rotation sensor 847 for detecting the rotation speed of the engine 5 (camshaft position of the engine output shaft) are connected to the input side of the engine controller 811. The starter motor 848 and the glow heater 849 are connected to the output side of the engine controller 811.

  A liquid crystal panel and various alarm lamps in the meter panel 39 are connected to the output side of the meter controller 812. Then, the meter controller 812 outputs various signals to the meter panel 39, and controls alarm lamp turn-on / off operation, flashing operation, liquid crystal panel display operation, alarm buzzer alarming operation, and the like.

  On the input side of the rectilinear controller 813, there are a main shift sensor (main shift potentiometer) 822 for detecting the operation position of the main shift lever 50, and a straight pick-up rotation sensor (straight vehicle speed sensor) for detecting the rotation speed (straight vehicle speed) of the straight output. 823, a forward / reverse sensor (forward / reverse potentiometer) 825 for detecting the operation position of the forward / reverse switching lever 36, a sub-transmission sensor 826 for detecting the operation position of the sub-transmission lever 45, and a creep for detecting the operation position of the ultra-low speed lever 44) Sensor 827, brake position sensor 828 for detecting the depression amount of brake pedal 35, clutch position sensor 829 for detecting the depression amount of clutch pedal 37, brake switch 851 for detecting depression of brake pedal 35, and depression of clutch pedal 37 are detected. Clutch switch 852 and parking blur Connecting the parking brake switch 853 for detecting the operation of a Kireba 43.

  On the output side of the rectilinear controller 813, a forward low speed clutch electromagnetic valve 632 that operates the forward low speed hydraulic clutch 537, a forward high speed clutch electromagnetic valve 633 that operates the forward high speed hydraulic clutch 539, and a reverse clutch electromagnetic valve that operates the reverse hydraulic clutch 541. 634 and a main transmission hydraulic pressure switching valve 624 that operates the main transmission hydraulic cylinder 524 in accordance with the tilting operation amount of the main transmission lever 50 is connected.

  On the input side of the turning controller 814, there is an emergency stop switch 58 for emergency stop of the traveling machine body 2 in an emergency, a steering angle sensor (steering potentiometer) 821 for detecting the turning amount (steering angle) of the steering handle 9, and a turning output. A turning pickup rotation sensor (turning vehicle speed sensor) 824 for detecting the number of rotations (turning vehicle speed) is connected. On the other hand, on the output side of the turning controller 814, the electric actuator 303 that controls the turning of the turning clutch mechanism 300 and the turning hydraulic pressure switching valve 742 that operates the turning hydraulic cylinder 741 according to the rotational operation amount of the steering handle 9. Is connected.

  On the input side of the work machine controller 810, the work machine elevating lever 34, the PTO clutch switch 53, the work machine elevating switch 57, a rolling sensor 864 that detects the right and left inclination angle of the traveling machine body 2, and the ground work machine 18 with respect to the traveling machine body 2 A potentiometer type working unit position sensor 865 that detects a relative left / right inclination angle, and a potentiometer type lift angle sensor 866 that detects a rotation angle of the lift arm 120 that connects the hydraulic lifting mechanism 22 and the left / right lower link 23. Connected. A double-action control solenoid valve 432, a PTO clutch hydraulic pressure switching valve 641, a tilt control solenoid valve 647, a lift control solenoid valve 650, and a drop control solenoid valve 651 are connected to the output side of the work machine controller 810.

  As shown in FIG. 22, the rectilinear controller 813 includes a rectilinear travel calculation unit 831 that controls the output of a rectilinear transmission path having a hydraulic mechanical continuously variable transmission (first continuously variable transmission) 500, and steering of the steering handle 9. A memory 832 that stores a deceleration rate table TA that stores a deceleration rate of the straight vehicle speed with respect to a corner, and a communication interface 833 connected to the CAN communication bus 815 are provided. As shown in FIG. 23, the deceleration rate table TA in the memory 832 includes “spin turn mode (first mode)”, “brake turn mode (second mode)”, and “slow turn mode (third mode)” which will be described later. For the four modes of “travel mode (fourth mode)”, deceleration rates TA1 to TA4 of the straight vehicle speed with respect to the steering angle of the steering handle 9 are stored.

  The deceleration rate table TA shown in FIG. 23 shows the deceleration rate when the steering handle 9 is rotated to the right in each mode (when the tractor 1 turns right), but the steering handle 9 is rotated to the left. The same applies to the deceleration rate when the tractor 1 is turned (when the tractor 1 turns left). That is, when the steering handle 9 is rotated in the left and right directions (when the tractor 1 is turned left and right), the steering angle obtained by rotating the deceleration rate according to the designated mode from the neutral position (0 °) of the steering handle 9. Is read from the deceleration rate table TA to set the deceleration rate of the straight vehicle speed. Further, the deceleration rate is a ratio multiplied by the straight traveling speed. When the deceleration rate is 100%, the straight traveling speed is not decelerated, and the linear traveling speed is decelerated as the deceleration rate becomes lower. Further, the steering handle 9 is restricted to rotate by θe (for example, 250 °) or more from 0 ° to the left and right from the neutral position by a steering angle detection mechanism (steering box) 880.

  As shown in FIG. 23, the deceleration rate table TA is a neutral area (so-called play area) when the steering angle of the steering handle 9 is from 0 ° (neutral position) to θmi (for example, 15 °). , Dead zone), and the deceleration rates TA1 to TA4 of each mode are 100%. When the steering angle of the steering handle 9 is from θmi to θma (for example, 245 °), the operating range of the steering handle 9 is set, and the deceleration rates TA1, TA2, TA4 of the spin turn mode, the brake turn mode, and the traveling mode, respectively. Is decreased monotonously according to the steering angle, while the deceleration rate TA3 in the gentle turning mode is kept constant at 100%. That is, the steering angle θmi is the neutral position (0 °) in the control, and the steering angle θma is the maximum steering angle in the control. At this time, the rate of change of the deceleration rate with respect to the steering angle increases in the order of the travel mode, the brake turn mode, and the spin turn mode. Further, when the steering angle of the steering wheel 9 is from θma to θe, the maximum range of the steering wheel 9 is set. De3 (0 <De1 <De2 <De3 <100)%.

  As shown in FIG. 22, the turning controller 814 includes a turning travel calculation unit 841 that controls output of a turning system transmission path having a hydraulic continuously variable transmission (second continuously variable transmission) 701, and a steering angle of the steering handle 9. And a memory interface 842 for storing a turn / straight forward ratio table TB storing a turn / straight forward ratio between the straight vehicle speed and the turning vehicle speed, and a communication interface 843 connected to the CAN communication bus 815. As shown in FIG. 23, the turning / straight-running ratio table TB in the memory 842 includes “spin turn mode (first mode)”, “brake turn mode (second mode)”, “slow turn mode (third mode), which will be described later. ) ”And“ travel mode (fourth mode) ”, the turning / straight travel ratios TB1 to TB4 with respect to the steering angle of the steering wheel 9 are stored.

  Note that the turn / straight-line ratio table TB shown in FIG. 23 shows the turn / straight-line ratio when the steering handle 9 is rotated to the right in each mode (when the tractor 1 turns right). Yes. Further, the turning / straight-ahead ratio is a ratio that is multiplied by the straight-ahead speed decelerated by the deceleration rate. When the turning / straight-ahead ratio is 0, there is no turning speed and both the left and right traveling crawlers 3 have the same straight-ahead speed. Since the turning speed increases as the turning / straight ahead ratio increases, the speed difference between the left and right traveling crawlers 3 increases. In the following description, the turning / straight travel ratio is mainly described when the steering handle 9 is rotated to the right (when turning right), and turning when the steering handle 9 is rotated to the left (when turning left). / The straight-line ratio is supplemented with parentheses.

  As shown in FIG. 23, the turn / straight-forward ratio table TB indicates the turn / straight-forward ratio TB1 to TB4 of each mode in the neutral region where the steering angle of the steering handle 9 is 0 ° to θmi (−θmi to 0 °). And In the operation region of the steering handle 9 in which the steering angle of the steering handle 9 is θmi to θma (−θma to −θmi), the turn / straight forward ratio of each of the spin turn mode, the brake turn mode, the slow turn mode, and the travel mode TB1 to TB4 are monotonously increased according to the steering angle. At this time, the rate of change of the turn / straight travel ratio with respect to the steering angle increases in the order of the slow turn mode, the travel mode, the brake turn mode, and the spin turn mode.

  Further, in the maximum region where the steering angle of the steering wheel 9 is θma to θe (−θe to −θma), the turn / straight travel ratio becomes the maximum value Ra1 to Ra4 (minimum value −Ra1 to −Ra4) in each mode. . As shown in FIG. 23, the maximum turning / straight-line ratios Ra1 to Ra4 (-Ra1 to -Ra4) are such that 0 <Ra1 <Ra2 <Ra3 <Ra4 (-Ra4 <-Ra3 <-Ra2 <-Ra1 <0). When the steering angle of the control handle 9 is set to the maximum range, the maximum turning / straight forward ratio Ra1 (−Ra1) is obtained in the slow turning mode, and the maximum turning / straight forward ratio Ra2 (−Ra2) is set in the traveling mode. In the brake turn mode, the maximum turn / straight forward ratio Ra3 (-Ra3) is obtained, and in the spin turn mode, the maximum turn / straight forward ratio Ra4 (-Ra4) is obtained.

  In the straight-ahead controller 813, as shown in FIG. 24, the straight-ahead travel calculation unit 831 receives a signal from the forward / reverse sensor 825, recognizes which of “forward”, “neutral”, and “reverse” is designated, Receiving signals from the speed change sensor 826 and the creep sensor 827, it is recognized which one of “high speed”, “low speed”, “super low speed”, and “neutral” is designated (STEP 1). The straight travel calculation unit 831 receives a signal from the main speed change sensor 822 and calculates a target value of the straight vehicle speed (hereinafter referred to as “straight forward reference target value”) in the straight travel state (the steering angle is 0 °). (STEP 2).

  The rectilinear controller 813 receives the signal from the steering angle sensor 821 through the turning controller 814 by the communication interface 833, and gives the signal from the steering angle sensor 821 to the rectilinear travel calculation unit 831 (STEP 3). When the straight traveling calculation unit 831 receives the signal from the steering angle sensor 821 and recognizes the steering angle of the steering handle 9, it refers to the deceleration rate table TA in the memory 832 and controls the steering handle 9 in the designated mode. The deceleration rate of the straight vehicle speed corresponding to the steering angle is read (STEP 4).

  The straight travel calculation unit 831 then multiplies the straight deceleration reference target value based on the signal from the main transmission sensor 822 by the read deceleration rate, thereby obtaining a straight vehicle speed target value corresponding to the steering angle (hereinafter referred to as “straight travel target”). Value ”) is calculated (STEP 5). The “straight vehicle speed” in the straight travel reference target value and the straight travel target value is a relative speed of the rotational speed of the traveling transmission shaft 536 in the straight traveling mission case 17 with respect to the rotational speed of the engine 5.

  The straight traveling calculation unit 831 receives signals from the brake position sensor 828 and the clutch position sensor 829 and confirms whether or not the brake pedal 35 and the clutch pedal 37 are depressed (STEP 6). Then, the straight travel calculation unit 831 confirms whether or not the aircraft pedal is stopped on the brake pedal 35, whether or not the clutch pedal 37 is operated, and whether or not the forward / reverse switching lever 36 or the auxiliary transmission lever 45 is in the neutral position. (STEP7).

  The straight travel calculation unit 831 is operated when the aircraft is stopped, when the clutch pedal 37 is depressed, or when the forward / reverse switching lever 36 or the sub-shift lever 45 is in the neutral position (Yes in STEP 7). Then, a signal from the straight-ahead pickup rotation sensor 823 (hereinafter referred to as “straight-ahead actual measurement value”) is transmitted from the communication interface 833 to the turning controller 814 (STEP 8). Thereafter, in the case of forward movement, the straight traveling calculation unit 831 controls the operations of the forward low speed clutch electromagnetic valve 632, the forward high speed clutch electromagnetic valve 633, and the reverse clutch electromagnetic valve 634, and the forward low speed hydraulic clutch 537, the forward high speed clutch The hydraulic clutch 539 and the reverse hydraulic clutch 541 are disconnected (STEP 9).

  On the other hand, the straight travel calculation unit 831 has no airframe stop operation, no stepping operation on both clutch pedals 37, the forward / reverse switching lever 36 is in the forward position or the reverse position, and the auxiliary transmission lever 45 is When the vehicle is in any of the super low speed position, the low speed position, or the high speed position (No in STEP 7), the calculated straight target value is transmitted from the communication interface 833 to the turning controller 814 (STEP 10). Thereafter, the straight traveling calculation unit 831 controls the operations of the forward low-speed clutch electromagnetic valve 632, the forward high-speed clutch electromagnetic valve 633, and the main transmission hydraulic pressure switching valve 624 in the case of forward movement based on the calculated linear advance target value. In the case of reverse, the operations of the reverse clutch solenoid valve 634 and the main transmission hydraulic pressure switching valve 624 are controlled (STEP 11). As a result, all the hydraulic clutches 537, 539, and 541 are all in a power disconnected state, and the traveling drive force from the main transmission output shaft 512 is substantially zero (main clutch disengaged state).

  That is, in STEP 11, the straight travel calculation unit 831 outputs the straight travel path (rotation speed by the straight travel output shaft 30) based on the straight travel actual measurement value (signal from the straight travel pickup rotation sensor 823) and the straight travel target value. Is feedback controlled (main shift control). It should be noted that the rotational speed of the traveling transmission shaft 536 is confirmed from the signal from the straight-ahead pickup rotation sensor 823 based on the transmission gear ratio specified by the signals from the auxiliary transmission sensor 826 and the creep sensor 827, and compared with the straight-ahead target value. Thus, the output of the straight-ahead transmission path is controlled.

  In the turning controller 814, as shown in FIG. 24, the turning travel calculation unit 841 receives the signal from the steering angle sensor 821, and recognizes the steering angle of the steering handle 9 (STEP 51). The turning traveling calculation unit 841 refers to the turning / straight ahead ratio table TB in the memory 842, and reads the turning / straight forward ratio according to the steering angle of the steering handle 9 in the designated mode (STEP 52).

  Further, the turning controller 814 receives signals from the auxiliary transmission sensor 826 and the creep sensor 827 through the straight-line controller 813 by the communication interface 843, and provides the signals to the turning calculation unit 841 (STEP 53). The turning travel calculation unit 841 recognizes whether “high speed”, “low speed”, or “ultra-low speed” is designated as the sub-shift based on signals from the sub-shift sensor 826 and the creep sensor 827. The turning traveling calculation unit 841 reads the correction value of the turning / straight-ahead ratio from the memory 842 based on the designated sub-shift, and corrects the turning / straight-ahead ratio based on the designated sub-shift (STEP 54).

  Further, the turning controller 814 receives the straight target value or the straight measured value (signal from the straight pick-up pickup rotation sensor 823) calculated by the straight controller 813 by the communication interface 843, and gives it to the turning calculation unit 841 (STEP 55). ). The turning travel calculation unit 841 confirms the straight traveling vehicle speed from the straight traveling target value or the straight traveling actual measurement value, and calculates the turning target value to be the turning vehicle speed by multiplying the straight traveling vehicle speed by the corrected turning / straight traveling ratio (STEP 56). ). The “turning vehicle speed” in the turning target value is a relative speed of the rotational speed of the motor shaft 709 in the turning mission case 13 with respect to the rotational speed of the engine 5.

  When the turning travel calculation unit 841 calculates the turning target value, it controls the operation of the turning hydraulic pressure switching valve 742. At this time, the turning travel calculation unit 841 outputs the turning system transmission path (rotation by the motor shaft 709) based on the signal from the turning pickup rotation sensor 824 (hereinafter referred to as “turning actual measurement value”) and the turning target value. (Speed) is feedback controlled (turning control) (STEP 57).

  When the main speed control is being executed, the linear controller 813 switches the forward low-speed clutch solenoid valve 632 and the reverse clutch when the signal from the forward / reverse sensor 825 is switched from “forward to backward” or “backward to forward”. The electromagnetic valve 634 is controlled to switch between the forward low speed hydraulic clutch 537 and the reverse hydraulic clutch 541. As described above, when switching between the forward low speed hydraulic clutch 537 and the reverse hydraulic clutch 541, the linear controller 813 performs control so that one of the forward low speed hydraulic clutch 537 and the reverse hydraulic clutch 541 is always connected.

  At this time, the main shift hydraulic pressure switching valve 624 is controlled by changing the rectilinear reference target value (or the rectilinear target value) so that the main shift output shaft 512 and the travel relay shaft 535 are in the lowest speed rotation state, and then again. The rotational speeds of the main transmission output shaft 512 and the travel relay shaft 535 are increased so that the original rotational speed is obtained. Therefore, the turning controller 814 can change the turning target value in the same way as the straight traveling target value by receiving the straight traveling target value from the straight traveling controller 813. Thereby, the turning controller 814 can reverse the output (turning vehicle speed) of the turning system transmission path with respect to the operation of the steering handle 9 when the traveling machine body 2 moves forward and backward, thereby contributing to smooth controllability to the operator.

  When the main shift control is being executed and the signal from the forward / reverse sensor 825 is in the “forward” state and the main shift lever 50 is operated to the high speed side or the low speed side, the linear controller 813 performs the forward low speed clutch electromagnetic. The valve 632 and the forward high speed clutch electromagnetic valve 633 are controlled to switch the forward low speed hydraulic clutch 537 and the forward high speed hydraulic clutch 539. As described above, when switching between the forward low speed hydraulic clutch 537 and the forward high speed hydraulic clutch 539, the linear advance controller 813 performs control so that one of the forward low speed hydraulic clutch 537 and the forward high speed hydraulic clutch 539 is always connected.

  At this time, the rectilinear controller 813 controls the main transmission hydraulic pressure switching valve 624 in accordance with the rectilinear target value. In addition, the turning controller 814 receives the straight target value from the straight controller 813 to set the output (turning vehicle speed) of the turning system transmission path for the operation of the steering handle 9, so that the forward low-speed hydraulic clutch 537 and the forward high-speed hydraulic pressure are set. Without affecting the switching of the clutch 539 and without performing complicated calculations, the output of the turning system transmission path (turning vehicle speed) corresponding to the output of the straight traveling system transmission path (straight traveling vehicle speed) can be achieved.

  When the forward controller 813 controls the forward low-speed hydraulic clutch 537, the forward high-speed hydraulic clutch 539, and the reverse hydraulic clutch 541 to be disengaged by depressing the clutch pedal 37 or the like, The signal from the pickup rotation sensor 823 is transmitted to the turning controller 814. Then, the turning controller 814 sets the output (turning vehicle speed) of the turning system transmission path based on the actually measured value (signal from the straight-forward pickup rotation sensor 823). Therefore, even if the forward high speed hydraulic clutch 539 and the reverse hydraulic clutch 541 are all disconnected, and the output of the straight transmission path (straight vehicle speed) does not correspond to the straight target value, the output of the turning transmission path ( (Turning vehicle speed) can be set optimally, so that the operator can operate the vehicle without a sense of incongruity.

  When the brake pedal 35 is depressed and the airframe is stopped by a sudden brake operation or the like, the straight-forward controller 813 is configured to advance the forward low-speed hydraulic clutch 537, the forward high-speed hydraulic pressure in a high speed region where the traveling speed (straight forward vehicle speed) is equal to or higher than a predetermined speed. Control is performed so that each of the clutch 539 and the reverse hydraulic clutch 541 is disengaged. At this time, the turning controller 814 sets the output (turning vehicle speed) of the turning system transmission path based on the straight-running actual measurement value (signal from the straight-travel pickup rotation sensor 823). Accordingly, when the braking control by the operation of the brake pedal 35 is being executed, the output of the turning system transmission path (turning vehicle speed) is obtained even if the output of the straight traveling system transmission path (straight traveling vehicle speed) does not correspond to the straight traveling target value. Since the vehicle can be decelerated in accordance with the output (straight vehicle speed) of the straight transmission path, the operator can operate the vehicle without a sense of incongruity.

  On the other hand, even when the airframe stop operation is performed on the brake pedal 35, if the traveling speed (straight traveling vehicle speed) falls in a low speed region below a predetermined speed, the straight traveling controller 813 adjusts to the vehicle's forward / backward travel. Thus, with the forward low-speed hydraulic clutch 537 or the reverse hydraulic clutch 541 connected, the linear advance target value is set so that the pump swash plate 523 of the hydraulic mechanical continuously variable transmission 500 is in a neutral state (0 °). Shift control (feedback control) is executed. At this time, the turning controller 814 may set the output of the turning system transmission path (turning vehicle speed) based on the straight traveling actual measurement value, or may set the output of the turning system transmission path based on the straight traveling target value.

  The turning controller 814 decelerates the output (turning vehicle speed) of the turning system transmission path as the output (straight running vehicle speed) of the straight running system transmission path is reduced. When the steering handle 9 is operated, the turning controller 814 increases the output of the turning transmission path (turning vehicle speed), and the turning controller 814 reduces the output of the straight driving transmission path (straight vehicle speed). Based on the turning angle (steering angle) of the steering handle 9, the speed ratio of the left and right traveling crawlers 3 during turning is determined.

  In addition, the operator operates the operation monitor 55 so that when the steering angle is large, the inside of the turn can be reversed to make a small turn (spin turn), and the spin turn mode (first mode). "Brake turn mode (2nd mode)" that can be executed up to the brake turn that stops the inside of the turn when the steering angle is close to the maximum when the steering angle is close to the maximum, and even more dull than the brake turn mode " A “slow turning mode (third mode)” and a “traveling mode (fourth mode)” that can handle high vehicle speeds can be selected. In addition, when ultra-low speed driving or low-speed driving is designated by the ultra-low speed lever 44 and the auxiliary transmission lever 45, the turning operation by any of the “spin turn mode”, “brake turn mode”, and “slow turning mode” is performed. Allowed. On the other hand, when high speed traveling is designated by the ultra low speed lever 44, only the turning operation in the “traveling mode” is permitted.

  Furthermore, the operator can adjust the turning force during turning in a plurality of stages by operating the operation monitor 55. Accordingly, the operator can select one of a plurality of modes by operating the operation monitor 55, and can also make stepwise adjustments. Therefore, an appropriate traveling characteristic (turning characteristic) suitable for the field situation or the like is possible. Can be selected easily.

  When “spin turn mode” is designated, when the turning angle of the steering handle 9 becomes the angle θt1 (θmi <θt1 <θma), the inner traveling crawler 3 is stopped and the traveling aircraft body 2 is turned by a brake turn. When the turning angle of the steering handle 9 exceeds the angle θt1, the inner traveling crawler 3 is reversely rotated, and the traveling aircraft body 2 is turned by a spin turn. When “brake turn mode” is designated, when the turning angle of the steering handle 9 becomes an angle θt2 (θt1 <θt2 <θma) close to the maximum control angle θma, the traveling machine body 2 is turned by a brake turn. . When the “slow turning mode” is designated, even if the turning angle of the steering handle 9 is set to be equal to or greater than the maximum control angle θma, the inner traveling crawler 3 is not stopped and the traveling machine body 2 is gently turned. Further, even in the “traveling mode”, the turning operation by the brake turn and the spin turn cannot be executed.

  When the turning controller 814 calculates the turning target value in STEP 56, the output from the hydraulic mechanical continuously variable transmission 500 is interrupted by the power transmission mechanism in the straight traveling mission case 17 (straight traveling transmission path). The reverse rotation operation by the inner traveling crawler 3 is prohibited. Thereby, when the power transmission in the straight traveling mission case 17 is interrupted, the reverse power output from the turning mission case 13 to the traveling crawler 3 can be limited, and the belief turning by the traveling machine body 2 is continuously performed. It can be prevented from being executed.

  The turning controller 814 executes emergency stop control for making an emergency stop when an abnormality occurs in the turning operation of the traveling machine body 2. At this time, the turning controller 814 compares the signal from the steering angle sensor 821 and the signal from the turning vehicle speed sensor 824 to confirm whether or not an abnormality has occurred in the turning operation of the traveling machine body 2. If an abnormality has occurred in the turning operation of the traveling machine body 2, the straightening controller 813 is instructed to set the straight traveling speed to 0, and the turning clutch mechanism 300 is disconnected. Below, the emergency stop control by the turning controller 814 is demonstrated with reference to the flowchart of FIG.

  As shown in FIG. 25, the turning controller 814 receives a signal from the steering angle sensor 821, and also receives a signal from the turning vehicle speed sensor 824, and a target turning amount based on the turning angle (steering angle) of the steering handle 9. Are compared with the actual turning amount (STEP 201 to STEP 203). At this time, when the target turning amount based on the steering angle and the actual turning amount in the traveling machine body 2 are significantly different (NO in STEP 203), the turning controller 814 determines that the turning operation of the traveling machine body 2 is abnormal. To do. Then, after an emergency stop alarm is notified to the meter panel 39 via the meter controller 812 (STEP 204), a command is given to the straight-ahead controller 813 to set the straight-ahead speed to 0 (STEP 205).

  Thereafter, the turning controller 814 notifies the operator by displaying on the meter panel 39 via the meter controller 812 so as to operate the brake pedal 35 (STEP 206). When the turning controller 814 receives signals from the brake position sensor 828 and the brake switch 851 and confirms that the braking force is applied by the straight brake mechanism 751 (Yes in STEP 207), the turning controller 814 sends a signal to the electric actuator 303. Then, the turning clutch mechanism 300 is disconnected (STEP 208).

  The turning controller 814 disconnects the turning clutch mechanism 300 and then receives a signal from the turning vehicle speed sensor 824 (STEP 209). Based on the signal from the turning vehicle speed sensor 824, the turning controller 814 determines whether the turning vehicle speed has become zero. Confirm (STEP 210). If the turning vehicle speed does not become zero until the predetermined time TX elapses after the turning of the turning clutch mechanism 300 is started (No in STEP 210 and Yes in STEP 211), the engine controller 811 is used. The engine 5 is stopped (STEP 212).

  The predetermined time TX may be a time until the cam mechanism 334 of the clutch position switching mechanism 330 rotates and the turning clutch mechanism 300 is reliably disconnected. That is, when the turning clutch mechanism 300 operates normally, the time required for the hydraulic continuously variable transmission 701 to stop is set as the predetermined time TX, whereby the turning clutch mechanism 300 and the hydraulic continuously variable transmission are set. It can be confirmed that an abnormality has occurred in the turning system transmission path including the machine 701. Therefore, the engine 5 can be stopped and the traveling of the tractor 1 can be stopped safely. Further, even when the turning machine clutch mechanism 300 is disconnected, if the turning speed does not become zero after the predetermined time TX is exceeded, an abnormality may occur in the hydraulic operation of the hydraulic continuously variable transmission 701. The tractor 1 can be safely stopped by determining that the engine 5 is stopped.

  The tractor 1 according to the present embodiment disconnects the turning clutch mechanism 300 when an abnormality occurs in the driving of the traveling crawler 3, so that the unintended turning operation of the operator can be prevented, and the tractor 1 can be safely operated when an abnormality occurs. Emergency stop can be made. At this time, when an abnormality occurs in the driving of the traveling crawler 3, the straight power by the straight hydraulic machine continuously variable transmission 500 is stopped, and then the turning clutch mechanism 300 is disconnected to stop the turning power. Let Therefore, not only the straight traveling operation of the traveling machine body 2 is stopped but also the turning operation is stopped, so that unexpected turning of the operator can be prevented and an emergency stop can be executed safely.

  In the present embodiment, the emergency stop control has been described by taking the control operation based on the flowchart of FIG. 25 as an example. For example, as shown in the flowchart of FIG. There may be. In this case, as shown in FIG. 26, when an abnormality is confirmed in the turning operation of the traveling machine body 2 (NO in STEP 203), an emergency stop alarm is notified through the meter panel 39 (STEP 204). The operation to the emergency stop switch 58 is confirmed (STETP230 to STEP231). Then, when an operation to the emergency stop switch 58 is received (Yes in STEP 231), the process proceeds to STEP 205, where the straight traveling speed and the turning speed are set to 0, and the traveling of the traveling machine body 2 is stopped. Thus, since the operator can stop the traveling of the traveling machine body 2 by operating the emergency stop switch 58, the operator can consciously stop the tractor 1 safely.

  Further, when the engine 5 is started with the auxiliary transmission gear mechanism 503 capable of transmitting power, the engine 5 can be started with the turning clutch mechanism 300 connected. Therefore, when the tractor 1 is operated at a low speed or an ultra-low speed for indoor work or the like, the engine 5 is started in a turnable state, so that the traveling body 2 can be turned at the same time as the engine 5 is started, and the work efficiency is improved. In addition, the unintended behavior of the operator can be prevented.

  Furthermore, the structure of each part in this invention is not limited to embodiment of illustration, A various change is possible in the range which does not deviate from the meaning of this invention.

2 traveling machine body 3 traveling crawler 5 engine 8 cabin 9 steering handle 13 turning mission case 17 straight traveling mission case 300 turning clutch mechanism 301 clutch input shaft 302 turning shifter 303 electric actuator 304 main clutch 305 buffer clutch 306 clutch output shaft 307 Clutch relay shaft 308 Clutch input claw portion 309 Clutch output claw portion 310 Thrust bearing 311 Insertion hole 312 Connection hole 313 Insertion hole 314 Spring 315 Spring stop ring 316 Locking groove 317 Stepped portion 318 Spring stop ring 319 Spring 320 Press ring 321 For turning Brake mechanism 322 Stepped portion 330 Clutch position switching mechanism 331 Shifter control shaft 332 Input arm 333 Relay arm 334 Cam 335 Output arm 336 Roller 337 Housing 338 Model Motor shaft 339 protruding portions 340 elongated hole 341 cam shaft 342 bearing portion 500 hydromechanical CVT (HMT)
501 Forward / reverse switching mechanism 502 Creep transmission gear mechanism 503 Sub transmission gear mechanism 511 Main transmission input shaft 512 Main transmission output shaft 521 Hydraulic pump section 522 Hydraulic motor section 523 Pump swash plate 524 Main transmission hydraulic cylinder 526 Planetary gear mechanism 535 Travel relay shaft 537 Forward low speed hydraulic clutch 539 Forward high speed hydraulic clutch 541 Reverse hydraulic clutch 624 Main transmission hydraulic pressure switching valve 642 Forward low speed clutch hydraulic pressure switching valve 643 Forward high speed clutch hydraulic pressure switching valve 644 Reverse clutch hydraulic pressure switching valve 701 Hydraulic continuously variable transmission (HST)
702 Differential gear mechanism 703 Planetary gear mechanism 704 Hydraulic pump unit 705 Hydraulic motor unit 706 Pump shaft 707 Charge pump 708 Pump swash plate 709 Motor shaft 741 Swing hydraulic cylinder 742 Swing hydraulic switching valve 751 Brake mechanism

Claims (4)

An engine mounted on the traveling machine body, a traveling unit that is driven based on the power of the engine , a first continuously variable transmission that shifts an output from the engine and outputs power for straight travel, and an output from the engine A second continuously variable transmission that outputs turning power and a power combining mechanism that combines the straight driving power and the turning power, and the left and right travels by the power from the power combining mechanism In a work vehicle that drives the parts independently,
A turning clutch mechanism is provided between the engine and the second continuously variable transmission,
A work vehicle characterized in that the turning clutch mechanism is disconnected when an abnormality occurs in the driving of the traveling unit.   When an abnormality occurs in driving of the traveling unit, the straight power by the first continuously variable transmission is stopped, and then the turning clutch mechanism is disconnected to stop the turning power. The work vehicle according to claim 1. Claims wherein the turning amount by the running section, when it becomes the turning amount and the mismatch which is set with respect to the steering angle of the steering longitudinal handle, abnormalities in the driving of the traveling unit and judging as that generated Item 3. The work vehicle according to Item 2. Straight brake mechanism is provided between the power combining mechanism straight advancing clutch mechanism, when an abnormality occurs in the driving of the traveling portion, is input to the power combining mechanism by the rectilinear brake mechanism The work vehicle according to any one of claims 1 to 3, wherein the turning clutch mechanism is disconnected after the straight driving power is braked.

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